Matter, Atoms and the Periodic Table

Matter and Classification Matter is anything that has mass and takes up space. Matter Pure Substance Element Compound Mixture Homogeneous Solution Heterogeneous Mechanical Suspension For further terminology information, see p. 143 of textbook

Physical and Chemical Properties Physical Properties of Matter Chemical Properties of Matter Boiling Point Melting Point Colour State (solid, liquid, gas) Malleability Conductivity Solubility Ductility Crystal Formation Ability to burn (combust) – emission of heat, light, flame Reaction with water Reaction to heating Flash point – lowest temperature in which a flammable liquid will ignite in air Behaviour in air

Matter and Atoms Matter is made up of tiny units called atoms. Atoms of one element differ from atoms of a different element (eg. physical & chemical properties). Atoms are made up of subatomic particles: Protons (positive charge of 1+) Electrons (negative charge of 1-) Neutrons (neutral, no charge) Atoms have an inner nucleus, where protons and neutrons are held. Outside this, electrons orbit in cloud-like energy levels (shells) that surround the nucleus. Copper and Gold

Periodic Table Metalloid (semi-metal)

Periodic Table Elements within the same group (columns) have similar properties because they have the same number of valence electrons (electrons in their outer shell). Elements in the same period (rows) do NOT have similar properties. The period number indicates the number of electron shells. Four common chemical families (groups): Alkalis (Group 1) – silver-grey, soft, react with H2O as well as O2 (hydrogen not included in this group) Alkalines (Group 2) – silver-grey, less reactive and a bit harder than Group 1 Halogens (Group 17) – colored, very reactive Noble gases (Group 18) – inert (very unreactive), colorless, odorless gases

Elements on the Periodic Table Atomic Number – number of protons in an atom of an element Eg. Boron’s atomic number is 5, therefore, it has 5 protons Atomic Mass – average mass of an atom of that element Number of protons + number of neutrons = atomic mass Eg. Boron’s atomic mass is 10.82 Ion Charge An ion is an atom that has either a positive (cation) or negative (anion) charge An atom has a charge when electrons are: Lost (results in positive charge) Gained (results in negative charge) Eg. Boron can only form one ion in which it will lose 3 electrons to become 3+ Ion charge Atomic number Atomic mass

Bohr Rutherford Diagrams Shows the arrangement and number of electrons in shells 1st shell: maximum 2 electrons 2nd shell: maximum 8 electrons 3rd shell: maximum 8 electrons 4th shell: maximum 2 electrons Hence, “2, 8, 8, 2 rule” To determine the number of electrons to draw, it is equivalent to the number of protons for that element! Number of neutrons: Atomic mass – number of protons Draw Bohr Rutherford diagrams for: Carbon atom Potassium atom Fluorine ion