Pre-IB Chemistry 1

vertical columns on periodic table

groups, families

horizontal rows on periodic table

periods

contains elements with similar chemical properties

groups

physical and chemical properties change somewhat regularly

periods

Properties:

Good conductor, malleable, most solids, and ductile

metal

Properties:

bad conductors, most gases, brittle if solid

nonmetal

Properties:

semiconductors of electricity, solids

metalloid

unreactive, gases at room temp., group 18 of periodic table

Noble Gases

substance that can be broken down into simpler and stabler substances, composed of the atoms of two or more elements

compound

mass is neither created nor destroyed during ordinary chemical reactions or physical changes

Law of conservation of mass

a chemical compound contains the same elements in exactly the same proportions by mass regardless of the size of the sample or source of the compound

Law of definite proportions

if two or more different compounds are composed of the same two elements, then the ratio of the masses of the second element combined with a certain mass of the first element is always a ratio of small whole numbers

Law of multiple proportions

indicates the elements present in a compound the relative number of atoms or ions of each element present in a compound

chemical formula

equal to the combined atomic masses of the elements present in a compound

formula mass

equal to the mass in grams per one mole

molar mass

smallest unit of an element maintaining the chemical identity of a substances

atom

pure substance that cannot be broken down into simpler, stabler substances

element

dependent on the amount of matter present

Extensive properties

independent of the amount of matter present

intensive properties