MET5 - Atomic Model

of quantum mechanics

Atomic Model

Content

Atomic models

Properties of the atom

The Atom

Atomic models

Quantum model

Bohr

Rutherford

thompson

Dalton

Democritus

Atomic Models

The ATOM

• Basic unit of all the matter.
• Will always keep the properties of the element.
• Electrically neutral

The Atom

Neutrons

Protons

Nuclear force

Electrons

Subatomic particles

Energy Shells

Also called energy levels

• Tridimensional regions around the nucleus (electron clouds), where there is a higher probability to find electrons.
• Electrons do not have a define trajectory

Energy Shells (Nee Atomic Orbitals)

14

10

From which shell appears

N° of orbitals per subshell

Max N° of e- per subshell

Info

energy Subshells

Atomic Mass

Atomic number

Atomic Mass Unit

Properties of the atom

molecules, ions and isotopes

Ions

Isotopes

Molecules

THANKS!!

• It is also called mass number
• It is expressed in "amu" or "u" units.
• Remember, not all the atoms have the same amount of neutrons.

Atomic mass (A)

The total number of protons and neutrons of any atom.

Molecules vs compounds

The atoms that form a molecule can be identical or different between each other.

Molecules

Group of two or more atoms held together by a chemical bond.

Isotopes

Atoms that has the same atomic number but different atomic mass

Isotopes

These atoms have the same chemical behavior.

• A force that keeps the neutrons and protons together.
• Strong enough to counteract the electrostatic repulsion of the protons.
• Larger the amount of protons in the nucleus weaken this force.

NUCLEAR FORCE

What keeps the nucleus together.

Each energy shell have four energy subshells. Defined as "s", "p", "d" and, "f". Each subshell have orbitals and can only contain 2 electrons.

Energy Shells

Atoms can have maximum seven energy levels or shells. The number of energy shells correspond to the number of periods in the Periodic Table

Atomic number (Z)

Number of protons in the nucleus of any atom

PROTON (p+)

• Particles with positive electric charge.
• They represent almost half of the mass of the nucleus.
• The number of protons (atomic number) in an element determine its location in the perioric table.
• Its mass is 1.67265x10-24 g

Valence number

Polyatomic ions

Monoatomic ions

Ions

Atom or group of atoms that has a net positive or negative charge.

The number of protons in the nucleus remain unchanged during the chemical reaction but, the atom loses or gains electrons. Positive Ions are called cations Negative ions are called anions

~ 0.0005

~ 1

~ 1

9.110x10-28

1.675x10-24

1.673x10-24

e-

n0

p+

u; amu

Mass (g)

• A measuring unit, like kg, liter, etc.
• The masses of the protons and neutrons are similar

Atomic Mass Unit (u; amu)

Defined as 1/12 of the mass of a Carbon atom (6 p+ and 6n0)

NEUTRON (n0)

• Particle without an electric charge.
• Help keep the structure of the nucleus together.
• They represent the other half of the mass of the nucleus.
• Its mass is 1.67495x10-24 g
• Not all the atoms have the same amount of neutrons.

ELECTRON (e-)

• Smallest particles with negative electric charge. ~2000 times smaller than a proton or neutron.
• They orbit around the nucleus in electron clouds.
• Represent the 0.054% of the mass of an atom.
• There must be the same number of electrons and protons for an atom to be neutral.
• They determine the chemical properties of the atom and form the chemical bonds.