Anything that has mass & M A T T E R Anything that has mass & occupies space

Mass Weight Stays Constant Measures quantity of matter Unit is kilogram (kg) or gram (g) Changes with location Measures the pull of gravity (which changes) on an object Unit is Newton (N)

Classification Substances Mixtures All matter can be classified into two groups Substances Mixtures

Substances Elements Compounds Cannot be broken down into other substances by ordinary chemical change 112 elements Many atoms of one type=Element Compounds Elements in compound are combined in definite proportions Always the SAME proportion for any given compound The compound has new properties different from the elements that make it up.

Have the SAME properties as any other pure sample of the same element Elements Compounds Have the SAME properties as any other pure sample of the same element Symbols H, O, As Have the SAME properties as any other pure sample of the compound Formulas: H2O, KCl, CO, CO2

H2O C12H22O11 C H Co As CO2

Consist of 2 or more substances that retain their individual properties

Homogenous Heterogeneous The mixture has the same composition throughout. Ex: Coffee is mixed thoroughly so that it is the same strength everywhere Heterogeneous The mixture has a different composition throughout. It is unevenly mixed. Ex.: Trail mix – you can pick out the raisins if you don’t want them.

Mixtures Only one set of properties Composition always fixed ex: H2O or Cl2 Always HOMOGENEOUS Each constituent keeps it own properties ex: sugar mixed in H20 Composition varies e.g. very sweet or a little sweet May be Homogeneous or Heterogeneous

M i x t u r e s Element + other element Compound + other compounds

Classification Scheme M A T T E R Mixtures Substances Homogenous Heterogeneous or Homogenous Element + Element Element + Compound Compound + Compound Element Compound

Element-Compound-Mixture? H2SO4 As (Arsenic) Aqueous (water-based) NaCl solution Sand + H2O Steel girders Steel = alloy Alloy is a solid solution of 2 or more metals C2H5OH Zinc washers (pure Zn)

How to interpret them and what they mean! Chemical Formulas How to interpret them and what they mean!

Two Special Cases of Elements: Monatomic vs. Diatomic Each molecule consists of a single atom. Element examples: Ne, Ar, Xe, Kr, Rn Metals: Mg, Zn, Fe, Co, Na Diatomic: Each molecule consists of two atoms. Element examples: H2, N2, Cl2

Diatomic Elements These elements have diatomic molecules – RECORD AND MEMORIZE!!!: Hydrogen -- H2 Oxygen -- O2 Nitrogen -- N2 Chlorine -- Cl2 Fluorine -- F2 Bromine -- Br2 Iodine -- I2

How to interpret Chemical Formulas What does H2O mean? There are H (hydrogen) and O (oxygen) in this compound. The small 2 (2) after the H means there are two hydrogens. The O with no number (you do NOT write 1) means there is one oxygen.

Some Examples: H2SO4 S8 CH4 NaCl NH4Br KNO3 MgCl2 CuFeS2 C6H6 NH3 ZnCl2 Fe