Is Anything That Has Mass and Occupies Space

Science Chemistry Unit

Review Lab safety and WHMIS symbols

Matter

is anything that has mass and occupies space.

Matter can be described using chemical and physical properties.

Light and heat energy is NOT matter because it is not made up of particles.

Physical properties

are those that can be observed or measured. For example, state, color, density. Know the different physical properties in Table 1.1 on page 18.

Chemical properties

are whether a substance can react with another to form a new product. Know the different chemical properties in Table 1.2 on page 19.

Theories vs Law

Laws

are descriptions of events or patterns that have been observed over and over again. Laws do not provide explanations, they simply state what happens. Laws are the same throughout time.

Theories

are explanations of observations that are supported by evidence. Theories can change as new information become available.

Atomic Theory

All matter is composed of particles called atoms.

(Everything you learned about the particle theory holds true in the atomic theory.)

What is an atom?

Atoms are composed of particles including protons, electrons and neutrons. Atoms have a tiny positive nucleus made up of protons and neutrons. Surrounding the nucleus are negatively charged electrons in specific energy levels.

Development of the Atomic Theory

Dalton (John)

- Proposed matter was made of small, hard spheres that are different for different elements. See Dalton’s Atomic Theory page 26

Thomson (J.J)

- Discovered electrons

- Proposed the “raison bun” model

- Atoms were positive charged balls (like the bun) with negative charges embedded in it (like the raisons)

Rutherford (Ernest)

- Discovered the nucleus

- Proposed that atoms were mostly “empty Space” with electrons moving about the nucleus.

- He later proposed that the nucleus contained protons and neutrons.

(see text page 27 to review his famous gold foil experiment.)

Bohr (Niels)

- Proposed that electrons surround the nucleus in specific energy levels or electron shells.

- Each electron has a particular amount of energy.

3 Subatomic Particles

Protons – positive charges found in the nucleus of the atom

Neutrons – neutral particles found in the nucleus.

Electrons – negative charged particles found in energy levels (shells) surrounding the nucleus.

The nucleus contains the most mass in an atom. Electrons occupy the most space (volume) in an atom.