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Ms. Grobsky WHS Chemistry Review of the Periodic Table Non-metals above the staircase Metals below the staircase Properties of Metals and Non-Metals Metals Shiny All but gold and copper are silver or grey in color Conduct electricity Ductile Malleable Lose electrons Non-metals Not shiny Most are colored Do not conduct electricity Not malleable Gain electrons Metals Non-Metals Structure of the Atom An atom consist of a positively-charged nucleus containing protons and neutrons and orbiting electrons Atomic number # of protons in an atom Unique for each element Remember, atoms on the periodic table are NEUTRAL Therefore, the atomic # = # of electrons Mass number # of neutrons + # of protons NOT the number on the Periodic Table – this is the average atomic mass Isotopes Different “versions” of the same element Vary in mass Same # of protons; different number of neutrons Calculating # of Protons, Electrons, and Neutrons P+ Na Hg K S Kr N E- More About Atoms Some elements are found in nature in their elemental form Most elements combine naturally with each other to become more energy-stable materials Atoms gain, lose, or share electrons with other atoms to become chemically stable Atoms of elements are not chemically stable until they have 8 electrons (octet rule) Hydrogen is an exception – only needs 2 electrons! Becoming an Ion If atoms gain or lose electrons, they form ions! Example Oxygen has 6 valence electrons Not chemically stable Oxide ion has 8 valence electrons Chemically stable Becoming a Magnesium Ion Magnesium achieves an octet by losing its two valence electrons With the loss of its two valence electrons, the magnesium ion has a +2 charge. Magnesium atom 12p+ 12e0 Magnesium ion 12p+ 10e2+ 12 Oxidation Numbers Defined as the overall charge of an ion after it has lost or gained electrons Metals lose electrons Non-metals gain electrons Can be determined by looking at the periodic table Predicting Oxidation Numbers Types of Compounds Ionic, Covalent, and Acids Types of Compounds Ionic Occurs when a metal loses all of its valence electrons to a non-metal Metal becomes positively-charged (cation) Non-metal becomes negatively-charged (anion) Covalent Two non-metals share electrons Neither loses or gains electrons – they share electrons Neither atom becomes an ion Oxidation #’s and Chemical Compounds When ions are combined together to form IONIC compounds, the overall charge of the compound that results MUST BE ZERO (neutral)!
