Matter and Change

Matter

• Anything that has mass and takes up space.

• Everything is made up of matter.

• Mass - amount of matter the object contains - measured in grams.

• Substance - matter that has uniform and definite composition (pure substances) - contain only one kind of matter.

Physical Properties

• Quality or condition of a substance that can be observed or measured without changing the substance’s composition.

• Color• odor• hardness• density• melting & boiling points• solubility

• Physical properties help chemists identify substances.

• Refer to page 29, Table 2.1

States of Matter

•Solid - definite shape and volume.– Particles are packed tightly

together.– Almost incompressible.– Expand only slightly when heated.

•Liquid - indefinite shape and definite volume.– In close contact with one

another.– Liquids can flow.– Almost incompressible.– Tend to expand when heated.

•Gas - indefinite shape and volume.– Gas particles are far apart.– Easily compressed.– Expand without limit to fill any space.– Vapor - describes the gaseous state of a

substance that is generally a liquid or solid at room temperature (different than a gas).

Physical Change

• Matter can be changed in many ways without changing the chemical composition of the material.

• Cutting • Dissolving • Crack• Grinding • Melting • Boiling • Bending • Freezing • Crush• Tearing • Condensing • Break

Melting or Freezing of Water

• Melting ice into liquid is a physical change, along with changing liquid to steam and steam to condensation.

• There is no alteration to the chemical composition of water, only a change of state.

Classifying Mixtures

• Physical blend of two more more substances.

• Compositions may vary.

Heterogeneous Mixture

• Not uniform in composition.• If you were to separate the mixture

into portions, each portion would be different from the other.

Homogeneous Mixture

• Completely uniform throughout.• Components are evenly distributed

throughout.• Separate the mixture into portions

and the portions would be the same.

• Also called solutions - may be gases, liquids, or solids.

Separating Mixtures

• Distillation - boil a liquid to produce a vapor that is then condensed back into a liquid. (see page 34 diagram)

• Evaporation - heterogeneous mixture of a solid and a liquid - heat the mixture to evaporate the liquid.

• Magnets - separate a metal from other solids.

Elements and Compounds

Elements

• Simplest forms of matter that can exist under normal laboratory conditions.

• Cannot be separated into simpler substances by chemical means.

• Building blocks of other substances.

Compounds

• Two or more elements combined together.

• Can be separated into simpler substances only by chemical means.

Chemical Symbols

• Shorthand representation of an element.• The symbol may be the first or the first two

letters of the name of the element.• Some symbols are representative of the Latin

or Greek names for the element.• Represented by one, two, or, less often,

three letters.– First letter is always capitalized.– Second or third letter is always lower case.

Chemical Symbols

• Elements you must know:– Hydrogen - Chromium - Zinc– Lithium - Manganese - Mercury– Sodium - Iron - Boron– Potassium - Cobalt - Aluminum– Magnesium- Nickel - Gallium– Calcium - Copper - Carbon– Strontium - Silver - Tin– Barium - Gold - Lead– Nitrogen - Oxygen - Sulfur– Phosphorus - Arsenic - Fluorine– Chlorine - Bromine - Iodine– Helium - Neon

Chemical Formulas

• Shorthand representation of a compound.• The subscript of a formula represents the

proportions of the various elements in the compound - the proportions are always the same for any one compound.

• H2O = water

• CO2 = carbon dioxide

• CO = carbon monoxide

Chemical Reactions

• One or more substances changing into new substances.

• Starting substances are the reactants.• Arrow dividing the two indicate “to

form” or “yields”.• Ending substances are the products.• Reactants Products

Chemical Property

• The ability of a substance to undergo a chemical reaction and to form new substances.

• Chemical properties are only observed when a substance undergoes a chemical change.

• A chemical change always results in a change in the chemical composition of the substances involved.

• Burning• Decompose• Rust• Explode• Corrode• Rot

Conservation of Mass

• Law of Conservation of Mass– In any physical change or chemical

reaction, mass is neither created nor destroyed; it is conserved.

– The mass of the reactants equals the mass of the products.