Mod 3&4

Anything that has mass & occupies space.

• 1. Pure substances-composed of only 1 atom or molecule.
• 2. Mixtures-2 or more mixtures physically mixed.

• 1. Single Element from the periodic table.
• 2. Compounds-substance made up of 2 or more elements.

• 1. Homogenous-composition is the same throughout the sample. ie air, peanut butter.
• 2. Heterogenous-composition varies throughout the sample. ie. chunky peanut butter.

Periods/Groups

Names of Groups

Shiny, ductile(can be drawn into a wire), malleable(can be flattened into a sheet), good conductors of heat and electricity, and has higher melting points and densities than nonmetals.

most are shiny, not very ductile or malleable(shatters if hammered), poor conductors of heat & electricity, melting points and densities are between metals and nonmetals.

Not shiny(some are solids, some are gases), not very ductile or malleable(shatters if hammered), poor conductors of heat & electricity, good insulators, and typically low melting points and densities.

Metal, metalloids, and non metals.

Same element with a different number of neutrons. Each element can have more then 1 isotope.

= to the number of protons in an atom. The number above the element abbreviation on the periodic table.

# of protons + neutrons

The avg mass of all naturally occuring isotopes. (The decimal number on the periodic table.)

Electrons close to the nucleus have the lowest energy. Electrons farther and farther out from the nucleus have greater and greater energy. Electrons with similar energy are grouped in energy levels.

Electrons in the outer most energy level. The group # indicates the number of valence electrons.

Any element with a number of e- that is different from the number of protons.

Positively charged ions.

Negatively charged ions.

The goal of any atom is to be stable(like the nobel gases). 8 electrons in the outer energy level- 8 valence electrons. Atoms can do this by gaining, losing, or sharing electrons.

Held together by strong attractions between oppositely charged ions, called ionic bonds.