The Composition of Matter: Building Blocks of the Universe

The Composition of Matter: Building Blocks of the Universe

What is Matter?

Matter is anything that has mass and occupies space. Everything around us, from the air we breathe to the computer or mobile device you are using to view this presentation, is composed of matter.

The States of Matter

Matter exists in different forms, referred to as states. These states include: Solids: Matter in the solid state has a fixed shape and volume. The particles in a solid are closely packed together and vibrate in place. Examples include rocks, metals, and ice. Liquids: Matter in the liquid state has a definite volume but can change shape based on its container. The particles in a liquid are less closely packed than in a solid and can move around each other. Examples include water, oil, and milk. Gases: Matter in the gaseous state can change both shape and volume. The particles in a gas are far apart and move freely. Examples include the air we breathe, helium, and steam.

Everyday Examples of Matter

Matter is everywhere in our daily lives and the natural world. For example, a pencil is made of matter in the solid state, including wood, graphite (for the "lead"), and a small amount of metal and rubber (for the eraser). The water you drink is liquid matter. The air around us is composed of gaseous matter, primarily nitrogen, oxygen, and smaller amounts of other gases.

The Building Blocks of Matter: Atoms

Atoms are the smallest units of matter that retain the properties of an element. They are composed of subatomic particles: protons, neutrons, and electrons. Protons carry a positive charge and are found in the nucleus of the atom. Neutrons, also located in the nucleus, carry no charge. Electrons, which carry a negative charge, move in regions around the nucleus known as electron shells.

Atomic Structure

An atom is made up of a nucleus, containing protons and neutrons, and electrons orbiting the nucleus in electron shells.

Protons, Neutrons, and Electrons

Protons carry a positive charge, neutrons have no charge, and electrons carry a negative charge. The number of protons in an atom determines the type of element it is.

The Role of Electrons

Electrons occupy specific energy levels, or shells, around the nucleus. These shells fill up in a specific order and the outermost electrons play a key role in chemical reactions.

The Atomic Number: Identifying an Element

The atomic number of an atom is determined by the number of protons in its nucleus. This number is unique for each element and is used to arrange elements in the periodic table.

Elements and Their Atomic Numbers

Every element on the periodic table has a unique atomic number. For example, hydrogen has an atomic number of 1 as it has only one proton in its nucleus. Oxygen, with 8 protons, has an atomic number of 8.

Importance of Atomic Number

The atomic number not only identifies an element, but also provides information about its properties. Elements with similar properties are arranged in the same group in the periodic table.

Atomic Number and Electron Configuration

The atomic number also tells us how many electrons an atom has in its neutral state. These electrons are arranged in shells around the nucleus. The arrangement of these electrons, particularly in the outermost shell, greatly influences an element's chemical behavior, including how it bonds with other atoms and its level of reactivity. For example, hydrogen (atomic number 1) has one electron in its outermost shell, while oxygen (atomic number 8) has six electrons in its outer shell.

Mixtures: Combining Different Types of Matter

A mixture is a combination of two or more different substances that have not reacted chemically and can be separated into their original components.

Homogeneous and Heterogeneous Mixtures

A homogeneous mixture has the same composition throughout, like air or a solution of sugar in water. A heterogeneous mixture consists of visibly different substances or phases, like oil and water, or a chocolate chip cookie.

Everyday Examples of Mixtures

Many things we encounter daily are mixtures. Air is a mixture of nitrogen, oxygen, and small amounts of other gases. Sea water is a mixture of water and various salts.