Valence electrons - electrons on the outer-most ring that have the highest energy. Electron dot diagram - includes the element symbol and dots for each valence electron. Stable Atom - an atom that has a full outer shell of 8 electrons ( 2 for H, He, Li, Be, and B) Neutral Atom - any atom from the periodic table. The number of protons = the number of electrons. + = -
Ionic Bonding - a bond where electrons are gained or lost and ions are formed. Ion - an atom that has gained or lost electrons and has a positive or negative charge. Na + Cl Na + Cl - Ions are hard, brittle solids with high melting points. When melted or dissolved in water, they conduct electricity.
Covalent Bond - when atoms share electrons. Usually between 2 nonmetals. H N + H N H NH 3 H Molecule - the neutral particle that is formed when atoms share electrons. Double bond -share 2 pairs of electrons. O=O Triple Bond -share 3 pairs of electrons.
Molecular compounds usually have lower melting and boiling points and do not conduct electricity. Polar bond- electrons are shared unequally. Nonpolar bond - electrons shared equally. H 2 O vs F 2
Alloy - a mixture made of two or more elements and at least one of which is a metal. They are usually stronger and less reactive. Metallic Bond - metal atoms combine in regular patterns where the valence electrons are tree to move from atom to atom. This free movement explains the characteristics of metals. - - + - - + - - + - - + - - + - - + - - + - - - + - - + - - + - -
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