Chemistry is the study of the properties and behavior of matter. Physical material of the universe Has mass Occupies space

Properties of Matter Physical properties: Measured without changing the substance (melting point, color) Chemical properties: Describe how substances react to form different substances (hydrogen burns in oxygen) Intensive properties: Do not depend on the amount of substance (melting point) Extensive properties: Depend on the amount of substance (mass, volume)

States of Matter (macroscopic level) Gas No fixed volume or shape compressible Liquid Volume independent of container, no fixed shape Incompressible Solid Volume and shape independent of container Incompressible, rigid

States of Matter (molecular level) Gas Molecules far apart, Move at high speeds, collide often Liquid Molecules closer than those in gas, Move rapidly but can slide over each other Solid Molecules packed closely in definite arrangements

Separation of Mixtures Separation techniques exploit differences in properties of the components Filtration: To remove solid from liquid Distillation: To boil off one or more components Chromatography: To exploit solubility of components

Elements & Compounds An element is a substance made of one kind of atom. Examples are oxygen and silicon. A compound is a substance made of two or more elements. Has different properties than those of the elements from which it is made. Example is SiO2 (glass or sand). Elements are combined in a specific proportion.

Compounds A compound is a substance of 2 or more elements, chemically combined. Plants make glucose. Geologic processes make calcium carbonate. Two types of compounds Molecular compounds Ionic compounds

Molecules A molecule is a particle of matter made up of two or more atoms held together by SHARING of electrons. N2 Nitrogen CO2 Carbon dioxide

Mixtures Mixtures are substances made of two or more parts. Not combined chemically Make-up or composition may vary (soil) Parts of mixtures keep their original properties. Parts can be separated by physical means. Distillation, evaporation and filtering are examples of physical means.

Mixture vs. Compound Mixture Compound Composition* may vary. Composition is constant. Components** keep their original properties. Properties are different than those of its components. Components are not chemically combined. Components are chemically combined. Components can be separated by physical means. Components usually require chemical means for separation. *Composition = how something is made. (Compose = To make.) **Component = a part *** vary = differ

Properties of Mixtures Can be made up of any number of compounds or elements. Homogeneous mixture: All parts are alike. Uniform Any sample contains same amount of each component. Milk and orange juice are examples. Heterogeneous mixture: Not every part has the same composition. Non-uniform One sample may have more of one component than another sample. Soil and garlic salt are examples.

Properties of Matter Physical properties: Measured without changing the substance (melting point, color) Chemical properties: Describe how substances react to form different substances (hydrogen burns in oxygen) Intensive properties: Do not depend on the amount of substance (melting point) Extensive properties: Depend on the amount of substance (mass, volume)

Classifying Substances Element, Mixture or Compound? Homogeneous or heterogeneous mixture? Ionic or molecular compound? Metal alloy (steel) mixture homogeneous Tin element Brass mixture (Cu,Zn) Carbon dioxide (CO2) compound molecular Calcium Carbonate (CaCO3) ionic Ammonia (NH3) Cement heterogeneous Ink Cola with ice

Periodic Table The modern periodic table shows the position of the element is related to : 1. Atomic number AND 2. Arrangement of electrons in its energy levels

Periodic Table Organization Nonmetals: Upper right corner plus hydrogen.  Metals: 80 % of elements to left of zig-zag line.  Metalloids: Have properties of both metals and nonmetals. They border the zig-zag line.   Rare Earth Metals: Two rows of elements separated to make it more convenient size. Period: Horizontal row of table   Group: Vertical column of table

Groups Predict Properties Alkali metals in Group I are the most reactive elements due to 1 valence electron Halogens in Group 17 combine with metals to form salts Noble gases in Group 18 are not reactive due to 8 valence electrons (2 for He) Elements behave chemically like those closest to them on the table, particularly in same group.

Properties of Metals 1.Malleable (can be shaped without breaking) 2.Ductile (can be pulled into wire) 3.Have luster (are shiny) 4.Conduct electricity (Electrons are free to move.) 5.Have a low number of electrons in their outer energy levels ( 1 to 3)

Nonmetals No luster Not good conductors Many valence electrons (4 or more) Carbon: Component of living things Entire branch of chemistry devoted compounds containing carbon: Organic Chemistry

Metalloids Along zig-zag line (not including Al) Have properties of metals and non-metals Often shiny like metals Conduct heat and electricity Common use is semiconductors, computer chips Semiconductors conduct electricity when other elements are incorporated into them