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Periodic Table
In the beginning...
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For many years, scientists looked for a good way to organize the elements. This became increasingly important as more and more elements were discovered. An ingenious method of organizing elements was developed in 1869 by a Russian scientist named Dmitri Mendeleev. Mendeleev’s method of organizing elements was later revised, but it served as a basis for the method that is still used today. Mendeleev was a teacher as well as a chemist. He was writing a chemistry textbook and wanted to find a way to organize the 63 known elements so it would be easier for students to learn about them. He made a set of cards of the elements, similar to a deck of playing cards. On each card, he wrote the name of a different element, its atomic mass, and other known properties. Mendeleev arranged and rearranged the cards in many different ways, looking for a pattern. He finally found it when he placed the elements in order by increasing atomic mass.
Mendeleev left blank for elements that had not yet been discovered when he created his table. He predicted that these missing elements would eventually be discovered. Based on their position in the table, he even predicted their properties.
The Modern Periodic Table
A periodic table is still used today to organize the elements. You can see a simple version of the modern periodic table in the Figure below. The modern table is based on Mendeleev’s table, except the modern table arranges the elements by increasing atomic number instead of atomic mass. Atomic number is the number of protons in an atom, and this number is unique for each element. The modern table has more elements than Mendeleev’s table because many elements have been discovered since Mendeleev’s time.
Each element is represented by its chemical symbol, which consists of one or two letters. The first letter of the symbol is always written in upper case, and the second letter—if there is one—is always written in lower case. For example, the symbol for copper is Cu. It stands for cuprum, which is the Latin word for copper. The number above each symbol in the table is its unique atomic number. Notice how the atomic numbers increase from left to right and from top to bottom in the table.
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Periods of the Modern Periodic
Table
Rows of the modern periodic table are called periods.
- From left to right across a period, each element has one more proton than the element before it.
- Some periods in the modern periodic table are longer than others.
- For example, period 1 contains only two elements: hydrogen (H) and helium (He).
- In contrast, periods 6 and 7 are so long that many of their elements are placed below the main part of the table. They are the elements starting with lanthanum (La) in period 6 and actinium (Ac) in period 7.
- Some of the elements in period 7 have recently been discovered and named.
- The number of each period represents the number of energy levels that have electrons in them for atoms of each element in that period.
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Periods of the Modern Periodic
In December 2015, the International Union of Pure and Applied Chemistry (IUPAC) verified the existence of four new elements 113, 115, 117, and 118 and approved their addition to the periodic table. These elements complete period 7 of the periodic table.
Here are the new element names and their origins:
- Element 113 was named Nihonium, symbol Nh, proposed by Japanese researchers after the Japanese word Nihon, which means Japan.
- A team of scientists from Russia and the United States named element 115, Moscovium, symbol Mc, after Moscow and element 117, Tennessine, symbol Ts, after Tennessee.
- The Russian team that discovered element 118 named it Oganesson, symbol Og, after Yuri Oganessian, a prolific element hunter.
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Groups of the Modern Periodic Table
Columns of the modern table are called groups. There are 19 groups. Elements in the same group have similar properties. For example:
- All elements in group 18 are colorless, odorless gases, such as neon (Ne). (Neon is the element inside the light in opening photo C.)
- In contrast, all elements in group 1 are very reactive solids. They react explosively with water,
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Classes of Elements
All elements can be classified in one of three classes: metals, metalloids, or nonmetals. Elements in each class share certain basic properties. Elements in the metals class can conduct electricity, whereas elements in the nonmetals class generally cannot. Elements in the metalloids class fall in between the metals and nonmetals in their properties. An example of a metalloid is arsenic (As). In the periodic table above, elements are color coded to show their class. As you move from left to right across each period of the table, the elements change from metals to metalloids to nonmetals.
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PERIODIC TABLE OF CHEMICAL ELEMENTS
He
Metals
Halogens
Actinids
Be
Li
Ne
Non metals
Noble gases
Metalloids
Lanthanides
Mg
Na
Al
Si
Cl
Ar
Ni
Mn
Fe
Ca
Zn
Cu
Sc
Co
Cr
Ga
Ti
Ge
As
Br
Se
Kr
Ag
Pd
Tc
Ru
Sr
Rb
Cd
Nb
Rh
Mo
In
Zr
Sn
Sb
Te
Xe
Ba
Cs
Hg
Au
Lu
Hf
Re
Os
Ir
Pt
Tl
Pb
Bi
Po
At
Rn
Ta
Ds
Bh
Hs
Ra
Fr
Cn
Rg
Lr
Db
Mt
Sg
Nh
Rf
Fl
Mc
Ts
Lv
Og
Uue
Ubn
La
Ce
Pr
Nd
Pm
Sm
Eu
Gd
Tb
Dy
Ho
Er
Tm
Yb
Ac
Th
Pa
Np
Pu
Am
Cm
Bk
Cf
Es
Fm
Md
No
What Are Metals?
Metals are elements that can conduct electricity. Metals are by far the largest of the three classes. In fact, most elements are metals. All of the elements on the left side and in the middle of the periodic table, except for hydrogen, are metals. There are several different types of metals, including alkali metals in group 1 of the periodic table, alkaline Earth metals in group 2, and transition metals in groups 3–12. The majority of metals are transition metals. Properties of Metals
Elements in the same class share certain basic similarities. In addition to conducting electricity, many metals have several other shared properties.
- Metals have relatively high melting points. This explains why all metals except for mercury are solids at room temperature.
- Most metals are good conductors of heat. That’s why metals such as iron, copper, and aluminum are used for pots and pans.
- Metals are generally shiny. This is because they reflect much of the light that strikes them. The mercury pictured above is very shiny.
- The majority of metals are ductile. This means that they can be pulled into long, thin shapes.
- Metals tend to be malleable. This means that they can be formed into thin sheets without breaking.
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PERIODIC TABLE OF CHEMICAL ELEMENTS
Metals
Halogens
Actinids
Be
Li
Non metals
Noble gases
Metalloids
Lanthanides
Mg
Na
Al
Ni
Mn
Fe
Ca
Zn
Cu
Sc
Co
Cr
Ga
Ti
Ag
Pd
Tc
Ru
Sr
Rb
Cd
Nb
Rh
Mo
In
Zr
Sn
Ba
Cs
Hg
Au
Hf
Re
Os
Ir
Pt
Tl
Pb
Bi
Ta
Ds
Bh
Hs
Ra
Fr
Cn
Rg
Db
Mt
Sg
Nh
Rf
Fl
Mc
Lv
What Are Nonmetals?
Nonmetals are elements that generally do not conduct electricity. Nonmetals are the second largest of the three classes after metals. They are the elements located on the right side of the periodic table. Because nonmetals are on the right side of the periodic table, they have more electrons in their outer energy level than elements on the left side or in the middle of the periodic table. The number of electrons in the outer energy level of an atom determines many of its properties.
- Nonmetals generally have properties that are very different from the properties of metals.
- Relatively low boiling point, which explains why many of them are gases at room temperature.
- However, some nonmetals are solids at room temperature,
- One nonmetal—bromine—is a liquid at room temperature.
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PERIODIC TABLE OF CHEMICAL ELEMENTS
Metals
Halogens
Actinids
Non metals
Noble gases
Metalloids
Lanthanides
Se
What Are Metalloids?
Metalloids are the smallest class of elements. There are just six metalloids. In addition to silicon, they include boron, germanium, arsenic, antimony, and tellurium. Metalloids fall between metals and nonmetals in the periodic table. They also fall between metals and nonmetals in terms of their properties. Chemical Properties of Metalloids
- How metalloids behave in chemical interactions with other elements depends mainly on the number of electrons in the outer energy level of their atoms.
- Metalloids have from three to six electrons in their outer energy level. Boron is the only metalloid with just three electrons in its outer energy level. It tends to act like metals by giving up its electrons in chemical reactions.
- Metalloids with more than four electrons in their outer energy level (arsenic, antimony, and tellurium) tend to act like nonmetals by gaining electrons in chemical reactions.
- Those with exactly four electrons in their outer energy level (silicon and germanium) may act like either metals or nonmetals, depending on the other elements in the reaction.
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Physical Properties of Metalloids
Most metalloids have some physical properties of metals and some physical properties of nonmetals. For example, metals are good conductors of both heat and electricity, whereas nonmetals generally cannot conduct heat or electricity. And metalloids? They fall between metals and nonmetals in their ability to conduct heat, and if they can conduct electricity, they usually can do so only at higher temperatures. Metalloids that can conduct electricity at higher temperatures are called semiconductors. Silicon is an example of a semiconductor. It is used to make the tiny electric circuits in computer chips. You can see a sample of silicon and a silicon chip in the Figure below.
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Metalloids tend to be shiny like metals but brittle like nonmetals. Because they are brittle, they may chip like glass or crumble to a powder if struck. Other physical properties of metalloids are more variable, including their boiling and melting points, although all metalloids exist as solids at room temperature.
PERIODIC TABLE OF CHEMICAL ELEMENTS
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Metals
Halogens
Actinids
Non metals
Noble gases
Metalloids
Lanthanides
Si
Ge
As
Sb
Te
Po
Halogens
Halogens are highly reactive nonmetallic elements in group 17 of the periodic table. The halogens include the elements fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At). All of them are relatively common on Earth except for astatine. Astatine is radioactive and rapidly decays to other, more stable elements. As a result, it is one of the least common elements on Earth.
Chemical Properties of Halogens The halogens are among the most reactive of all elements, although reactivity declines from the top to the bottom of the halogen group. Because all halogens have seven valence electrons, they are “eager” to gain one more electron. Doing so gives them a full outer energy level, which is the most stable arrangement of electrons. Halogens often combine with alkali metals in group 1 of the periodic table. Alkali metals have just one valence electron, which they are equally “eager” to donate. Reactions involving halogens, especially halogens near the top of the group, may be explosive.
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Physical Properties of Halogens
The halogen group is quite diverse. It includes elements that occur in three different states of matter at room temperature. Fluorine and chlorine are gases, bromine is a liquid, and iodine and astatine are solids. Halogens also vary in color, as you can see below. Fluorine and chlorine are green, bromine is red, and iodine and astatine are nearly black. Like other nonmetals, halogens cannot conduct electricity or heat. Compared with most other elements, halogens have relatively low melting and boiling points.
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Uses of Halogens: Most halogens have a variety of important uses
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PERIODIC TABLE OF CHEMICAL ELEMENTS
Metals
Halogens
Actinids
Non metals
Noble gases
Metalloids
Lanthanides
Cl
Br
At
Ts
Noble Gases
Noble gases are nonreactive, nonmetallic elements in group 18 of the periodic table. Noble gases include helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and radon (Rn). All noble gases are colorless and odorless. They also have low boiling points, explaining why they are gases at room temperature. Radon, at the bottom of the group, is radioactive, so it constantly decays to other elements.
Chemical Properties of Noble Gases: Noble gases are the least reactive of all known elements. That’s because with eight valence electrons, their outer energy levels are full. The only exception is helium, which has just two electrons. But helium also has a full outer energy level, because its only energy level (energy level 1) can hold a maximum of two electrons. A full outer energy level is the most stable arrangement of electrons. As a result, noble gases cannot become more stable by reacting with other elements and gaining or losing valence electrons. Therefore, noble gases are rarely involved in chemical reactions and almost never form compounds with other elements.
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Early incandescent light bulbs didn’t last very long. The filaments quickly burned out. Although air was pumped out of the bulb, it wasn’t a complete vacuum. Oxygen in the small amount of air remaining inside the light bulb reacted with the metal filament. This corroded the filament and caused dark deposits on the glass. Filling a light bulb with argon gas prevents these problems. That’s why modern light bulbs are filled with argon.
Noble gases are also used to fill the glass tubes of lighted signs like the one in the Figure below. Although noble gases are chemically nonreactive, their electrons can be energized by sending an electric current through them. When this happens, the electrons jump to a higher energy level. When the electrons return to their original energy level, they give off energy as light. Different noble gases give off light of different colors. Neon gives off reddish-orange light, like the word “Open” in the sign below. Krypton gives off violet light and xenon gives off blue light.
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PERIODIC TABLE OF CHEMICAL ELEMENTS
He
Metals
Halogens
Actinids
Ne
Non metals
Noble gases
Metalloids
Lanthanides
Ar
Kr
Xe
Rn
Og
Lanthanide Series
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The lanthanide series is known for being soft, silvery metals that are rather reactive. They have quite a bit of use including lasers, magnets, and eyeglass protection. In addition to these properties, the lanthanides are all found underneath the main group of elements on the periodic table. Lanthanides are the 15 elements located between atomic numbers 57 and 71. These elements are similar in both physical and chemical properties and can be found underneath the main group of elements on the Periodic table. The lanthanides are mostly special due to their electron configurations. They are one of only two groups that have valence electrons that can be found in the f-sublevel. Having these elements have electrons in the f-sublevel makes them all have similar properties.
Unearthing the Truth: The Sustainability Paradox of Rare Earths
The market size for global rare earth metals is expected to have a compounded annual growth rate of 10.2% from 2024 to 2023 — $3.39 billion to $3.74 billion. The Asia Pacific region had the highest market share at 86.14% in 2023. One reason the world is consuming more rare earth metals is the increasing demand for electronic devices, lithium-ion battery components and other green technologies. Likewise, rapid urbanization, industrialization and digitalization across the globe have boosted the need for these raw commodities. However, while rare earth elements — particularly lanthanides — are critical for emissions-reducing solutions for a healthier environment, a dire sustainability paradox is at play. Metal mining, especially, is the top toxic polluter in the U.S. It’s nearly impossible to extract these compounds without causing ecological damage. A standard extraction method involves removing topsoil and creating a leaching pool for harmful chemicals. These chemicals are used to separate the elements from ore. Unfortunately, the toxins usually enter groundwater, cause air pollution and drive erosion. Another strategy involves drilling holes into the ground and pumping chemicals into the Earth with polyvinyl chloride pipes. Yet, the residue ends up in a leaching pond, causing the same problems.
The situation can be even worse, considering rare earth elements occur near radioactive sources like thorium and uranium. The residual radioactive waste may leak into the surrounding ecosystems and contaminate vital water sources. According to the Harvard International Review, mining one metric ton of rare earth elements accumulates 13 kilograms of dust — about 28.7 pounds — and 9,600 to 12,000 cubic meters of waste gas. Another 75 cubic meters of wastewater is produced along with one metric ton of radioactive remnants. Experts are exploring ways to make extraction and processing methods of rare earths more environmentally safe and efficient. Likewise, they’re finding ways to recover these elements from waste using less harmful solvents. One solvent — hydrophobic deep eutectic solvent — can recover 96% of lanthanum and 98% of cerium. The metals were also 99.6% pure with little contamination.
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Lanthanides Are Crucial for Everyday Life: You may not often consider the importance of lanthanides in your everyday life, from the sunglasses you wear to protect your eyes to the television screen you watch. These rare earth elements are everywhere. Of course, if the world continues utilizing them in consumer goods, it is crucial to approach the mining process with cutting-edge solutions and adherence to sustainability principles.
PERIODIC TABLE OF CHEMICAL ELEMENTS
Metals
Halogens
Actinids
Non metals
Noble gases
Metalloids
Lanthanides
Lu
La
Ce
Pr
Nd
Pm
Sm
Eu
Gd
Tb
Dy
Ho
Er
Tm
Yb
Actinide Series
The Actinide series received its name from the first element in the set of elements. Actinium is the element at which the f orbitals begin and are disconnected from the rest of the table at that point. The actinides are technically located within the 7th horizontal period on the table. It is slightly difficult to visualize however because the actinides are traditionally removed and disconnected from the 7th period.
Actinides are a series of 15 radioactive, metallic elements (atomic numbers 89–103, actinium to lawrencium) located in the f-block of the periodic table, known for their instability, high density, and role in nuclear energy and weapons. Most are synthetic (transuranium elements), though thorium, protactinium, and uranium exist in nature. They are essential in nuclear power, smoke detectors, and medicine, but pose severe toxic and radioactive health risks. Environmental and Health Effects
Radioactive Danger: All actinides are toxic, primarily due to their radioactive nature, posing a risk of radiation poisoning, bone damage, and cancer, especially if inhaled or ingested.
Long-Term Waste: Due to their long half-lives, actinides contribute significantly to the radioactivity of spent nuclear fuel, causing long-term environmental storage issues. They form high-energy radioactive isotopes that are key components of spent fuel in nuclear reactors.
They are known as transuranic elements (elements after uranium).
They do not have any stable isotopes.
PERIODIC TABLE OF CHEMICAL ELEMENTS
Metals
Halogens
Actinids
Non metals
Noble gases
Metalloids
Lanthanides
Lr
Ac
Th
Pa
Np
Pu
Am
Cm
Bk
Cf
Es
Fm
Md
No
Periodic Table
Jane Kent
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Periodic Table
In the beginning...
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For many years, scientists looked for a good way to organize the elements. This became increasingly important as more and more elements were discovered. An ingenious method of organizing elements was developed in 1869 by a Russian scientist named Dmitri Mendeleev. Mendeleev’s method of organizing elements was later revised, but it served as a basis for the method that is still used today. Mendeleev was a teacher as well as a chemist. He was writing a chemistry textbook and wanted to find a way to organize the 63 known elements so it would be easier for students to learn about them. He made a set of cards of the elements, similar to a deck of playing cards. On each card, he wrote the name of a different element, its atomic mass, and other known properties. Mendeleev arranged and rearranged the cards in many different ways, looking for a pattern. He finally found it when he placed the elements in order by increasing atomic mass.
Mendeleev left blank for elements that had not yet been discovered when he created his table. He predicted that these missing elements would eventually be discovered. Based on their position in the table, he even predicted their properties.
The Modern Periodic Table
A periodic table is still used today to organize the elements. You can see a simple version of the modern periodic table in the Figure below. The modern table is based on Mendeleev’s table, except the modern table arranges the elements by increasing atomic number instead of atomic mass. Atomic number is the number of protons in an atom, and this number is unique for each element. The modern table has more elements than Mendeleev’s table because many elements have been discovered since Mendeleev’s time.
Each element is represented by its chemical symbol, which consists of one or two letters. The first letter of the symbol is always written in upper case, and the second letter—if there is one—is always written in lower case. For example, the symbol for copper is Cu. It stands for cuprum, which is the Latin word for copper. The number above each symbol in the table is its unique atomic number. Notice how the atomic numbers increase from left to right and from top to bottom in the table.
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Periods of the Modern Periodic
Table Rows of the modern periodic table are called periods.
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Periods of the Modern Periodic
In December 2015, the International Union of Pure and Applied Chemistry (IUPAC) verified the existence of four new elements 113, 115, 117, and 118 and approved their addition to the periodic table. These elements complete period 7 of the periodic table. Here are the new element names and their origins:
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Groups of the Modern Periodic Table
Columns of the modern table are called groups. There are 19 groups. Elements in the same group have similar properties. For example:
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Classes of Elements
All elements can be classified in one of three classes: metals, metalloids, or nonmetals. Elements in each class share certain basic properties. Elements in the metals class can conduct electricity, whereas elements in the nonmetals class generally cannot. Elements in the metalloids class fall in between the metals and nonmetals in their properties. An example of a metalloid is arsenic (As). In the periodic table above, elements are color coded to show their class. As you move from left to right across each period of the table, the elements change from metals to metalloids to nonmetals.
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PERIODIC TABLE OF CHEMICAL ELEMENTS
He
Metals
Halogens
Actinids
Be
Li
Ne
Non metals
Noble gases
Metalloids
Lanthanides
Mg
Na
Al
Si
Cl
Ar
Ni
Mn
Fe
Ca
Zn
Cu
Sc
Co
Cr
Ga
Ti
Ge
As
Br
Se
Kr
Ag
Pd
Tc
Ru
Sr
Rb
Cd
Nb
Rh
Mo
In
Zr
Sn
Sb
Te
Xe
Ba
Cs
Hg
Au
Lu
Hf
Re
Os
Ir
Pt
Tl
Pb
Bi
Po
At
Rn
Ta
Ds
Bh
Hs
Ra
Fr
Cn
Rg
Lr
Db
Mt
Sg
Nh
Rf
Fl
Mc
Ts
Lv
Og
Uue
Ubn
La
Ce
Pr
Nd
Pm
Sm
Eu
Gd
Tb
Dy
Ho
Er
Tm
Yb
Ac
Th
Pa
Np
Pu
Am
Cm
Bk
Cf
Es
Fm
Md
No
What Are Metals?
Metals are elements that can conduct electricity. Metals are by far the largest of the three classes. In fact, most elements are metals. All of the elements on the left side and in the middle of the periodic table, except for hydrogen, are metals. There are several different types of metals, including alkali metals in group 1 of the periodic table, alkaline Earth metals in group 2, and transition metals in groups 3–12. The majority of metals are transition metals. Properties of Metals Elements in the same class share certain basic similarities. In addition to conducting electricity, many metals have several other shared properties.
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PERIODIC TABLE OF CHEMICAL ELEMENTS
Metals
Halogens
Actinids
Be
Li
Non metals
Noble gases
Metalloids
Lanthanides
Mg
Na
Al
Ni
Mn
Fe
Ca
Zn
Cu
Sc
Co
Cr
Ga
Ti
Ag
Pd
Tc
Ru
Sr
Rb
Cd
Nb
Rh
Mo
In
Zr
Sn
Ba
Cs
Hg
Au
Hf
Re
Os
Ir
Pt
Tl
Pb
Bi
Ta
Ds
Bh
Hs
Ra
Fr
Cn
Rg
Db
Mt
Sg
Nh
Rf
Fl
Mc
Lv
What Are Nonmetals?
Nonmetals are elements that generally do not conduct electricity. Nonmetals are the second largest of the three classes after metals. They are the elements located on the right side of the periodic table. Because nonmetals are on the right side of the periodic table, they have more electrons in their outer energy level than elements on the left side or in the middle of the periodic table. The number of electrons in the outer energy level of an atom determines many of its properties.
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PERIODIC TABLE OF CHEMICAL ELEMENTS
Metals
Halogens
Actinids
Non metals
Noble gases
Metalloids
Lanthanides
Se
What Are Metalloids?
Metalloids are the smallest class of elements. There are just six metalloids. In addition to silicon, they include boron, germanium, arsenic, antimony, and tellurium. Metalloids fall between metals and nonmetals in the periodic table. They also fall between metals and nonmetals in terms of their properties. Chemical Properties of Metalloids
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Physical Properties of Metalloids
Most metalloids have some physical properties of metals and some physical properties of nonmetals. For example, metals are good conductors of both heat and electricity, whereas nonmetals generally cannot conduct heat or electricity. And metalloids? They fall between metals and nonmetals in their ability to conduct heat, and if they can conduct electricity, they usually can do so only at higher temperatures. Metalloids that can conduct electricity at higher temperatures are called semiconductors. Silicon is an example of a semiconductor. It is used to make the tiny electric circuits in computer chips. You can see a sample of silicon and a silicon chip in the Figure below.
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Metalloids tend to be shiny like metals but brittle like nonmetals. Because they are brittle, they may chip like glass or crumble to a powder if struck. Other physical properties of metalloids are more variable, including their boiling and melting points, although all metalloids exist as solids at room temperature.
PERIODIC TABLE OF CHEMICAL ELEMENTS
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Metals
Halogens
Actinids
Non metals
Noble gases
Metalloids
Lanthanides
Si
Ge
As
Sb
Te
Po
Halogens
Halogens are highly reactive nonmetallic elements in group 17 of the periodic table. The halogens include the elements fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At). All of them are relatively common on Earth except for astatine. Astatine is radioactive and rapidly decays to other, more stable elements. As a result, it is one of the least common elements on Earth.
Chemical Properties of Halogens The halogens are among the most reactive of all elements, although reactivity declines from the top to the bottom of the halogen group. Because all halogens have seven valence electrons, they are “eager” to gain one more electron. Doing so gives them a full outer energy level, which is the most stable arrangement of electrons. Halogens often combine with alkali metals in group 1 of the periodic table. Alkali metals have just one valence electron, which they are equally “eager” to donate. Reactions involving halogens, especially halogens near the top of the group, may be explosive.
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Physical Properties of Halogens
The halogen group is quite diverse. It includes elements that occur in three different states of matter at room temperature. Fluorine and chlorine are gases, bromine is a liquid, and iodine and astatine are solids. Halogens also vary in color, as you can see below. Fluorine and chlorine are green, bromine is red, and iodine and astatine are nearly black. Like other nonmetals, halogens cannot conduct electricity or heat. Compared with most other elements, halogens have relatively low melting and boiling points.
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Uses of Halogens: Most halogens have a variety of important uses
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PERIODIC TABLE OF CHEMICAL ELEMENTS
Metals
Halogens
Actinids
Non metals
Noble gases
Metalloids
Lanthanides
Cl
Br
At
Ts
Noble Gases
Noble gases are nonreactive, nonmetallic elements in group 18 of the periodic table. Noble gases include helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and radon (Rn). All noble gases are colorless and odorless. They also have low boiling points, explaining why they are gases at room temperature. Radon, at the bottom of the group, is radioactive, so it constantly decays to other elements.
Chemical Properties of Noble Gases: Noble gases are the least reactive of all known elements. That’s because with eight valence electrons, their outer energy levels are full. The only exception is helium, which has just two electrons. But helium also has a full outer energy level, because its only energy level (energy level 1) can hold a maximum of two electrons. A full outer energy level is the most stable arrangement of electrons. As a result, noble gases cannot become more stable by reacting with other elements and gaining or losing valence electrons. Therefore, noble gases are rarely involved in chemical reactions and almost never form compounds with other elements.
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Early incandescent light bulbs didn’t last very long. The filaments quickly burned out. Although air was pumped out of the bulb, it wasn’t a complete vacuum. Oxygen in the small amount of air remaining inside the light bulb reacted with the metal filament. This corroded the filament and caused dark deposits on the glass. Filling a light bulb with argon gas prevents these problems. That’s why modern light bulbs are filled with argon.
Noble gases are also used to fill the glass tubes of lighted signs like the one in the Figure below. Although noble gases are chemically nonreactive, their electrons can be energized by sending an electric current through them. When this happens, the electrons jump to a higher energy level. When the electrons return to their original energy level, they give off energy as light. Different noble gases give off light of different colors. Neon gives off reddish-orange light, like the word “Open” in the sign below. Krypton gives off violet light and xenon gives off blue light.
Next
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PERIODIC TABLE OF CHEMICAL ELEMENTS
He
Metals
Halogens
Actinids
Ne
Non metals
Noble gases
Metalloids
Lanthanides
Ar
Kr
Xe
Rn
Og
Lanthanide Series
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The lanthanide series is known for being soft, silvery metals that are rather reactive. They have quite a bit of use including lasers, magnets, and eyeglass protection. In addition to these properties, the lanthanides are all found underneath the main group of elements on the periodic table. Lanthanides are the 15 elements located between atomic numbers 57 and 71. These elements are similar in both physical and chemical properties and can be found underneath the main group of elements on the Periodic table. The lanthanides are mostly special due to their electron configurations. They are one of only two groups that have valence electrons that can be found in the f-sublevel. Having these elements have electrons in the f-sublevel makes them all have similar properties.
Unearthing the Truth: The Sustainability Paradox of Rare Earths The market size for global rare earth metals is expected to have a compounded annual growth rate of 10.2% from 2024 to 2023 — $3.39 billion to $3.74 billion. The Asia Pacific region had the highest market share at 86.14% in 2023. One reason the world is consuming more rare earth metals is the increasing demand for electronic devices, lithium-ion battery components and other green technologies. Likewise, rapid urbanization, industrialization and digitalization across the globe have boosted the need for these raw commodities. However, while rare earth elements — particularly lanthanides — are critical for emissions-reducing solutions for a healthier environment, a dire sustainability paradox is at play. Metal mining, especially, is the top toxic polluter in the U.S. It’s nearly impossible to extract these compounds without causing ecological damage. A standard extraction method involves removing topsoil and creating a leaching pool for harmful chemicals. These chemicals are used to separate the elements from ore. Unfortunately, the toxins usually enter groundwater, cause air pollution and drive erosion. Another strategy involves drilling holes into the ground and pumping chemicals into the Earth with polyvinyl chloride pipes. Yet, the residue ends up in a leaching pond, causing the same problems. The situation can be even worse, considering rare earth elements occur near radioactive sources like thorium and uranium. The residual radioactive waste may leak into the surrounding ecosystems and contaminate vital water sources. According to the Harvard International Review, mining one metric ton of rare earth elements accumulates 13 kilograms of dust — about 28.7 pounds — and 9,600 to 12,000 cubic meters of waste gas. Another 75 cubic meters of wastewater is produced along with one metric ton of radioactive remnants. Experts are exploring ways to make extraction and processing methods of rare earths more environmentally safe and efficient. Likewise, they’re finding ways to recover these elements from waste using less harmful solvents. One solvent — hydrophobic deep eutectic solvent — can recover 96% of lanthanum and 98% of cerium. The metals were also 99.6% pure with little contamination.
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Lanthanides Are Crucial for Everyday Life: You may not often consider the importance of lanthanides in your everyday life, from the sunglasses you wear to protect your eyes to the television screen you watch. These rare earth elements are everywhere. Of course, if the world continues utilizing them in consumer goods, it is crucial to approach the mining process with cutting-edge solutions and adherence to sustainability principles.
PERIODIC TABLE OF CHEMICAL ELEMENTS
Metals
Halogens
Actinids
Non metals
Noble gases
Metalloids
Lanthanides
Lu
La
Ce
Pr
Nd
Pm
Sm
Eu
Gd
Tb
Dy
Ho
Er
Tm
Yb
Actinide Series
The Actinide series received its name from the first element in the set of elements. Actinium is the element at which the f orbitals begin and are disconnected from the rest of the table at that point. The actinides are technically located within the 7th horizontal period on the table. It is slightly difficult to visualize however because the actinides are traditionally removed and disconnected from the 7th period.
Actinides are a series of 15 radioactive, metallic elements (atomic numbers 89–103, actinium to lawrencium) located in the f-block of the periodic table, known for their instability, high density, and role in nuclear energy and weapons. Most are synthetic (transuranium elements), though thorium, protactinium, and uranium exist in nature. They are essential in nuclear power, smoke detectors, and medicine, but pose severe toxic and radioactive health risks. Environmental and Health Effects Radioactive Danger: All actinides are toxic, primarily due to their radioactive nature, posing a risk of radiation poisoning, bone damage, and cancer, especially if inhaled or ingested. Long-Term Waste: Due to their long half-lives, actinides contribute significantly to the radioactivity of spent nuclear fuel, causing long-term environmental storage issues. They form high-energy radioactive isotopes that are key components of spent fuel in nuclear reactors. They are known as transuranic elements (elements after uranium). They do not have any stable isotopes.
PERIODIC TABLE OF CHEMICAL ELEMENTS
Metals
Halogens
Actinids
Non metals
Noble gases
Metalloids
Lanthanides
Lr
Ac
Th
Pa
Np
Pu
Am
Cm
Bk
Cf
Es
Fm
Md
No