chemistry
metals
most are shiny, silver or grey in colour (except gold and copper), good conductors of electricity and heat. Except for mercury, they are solids at room temperature, most are malleable and ductile, most react with acids.
non-metals
only 17 elements are non metals, 11 are gases, 5 are solids, and 1 is a liquid (bromine). Most solid non-metald are dull, but some are brightly coloured (sulfur). Solids are brittle. Usually poor conductors of electricity and heat.
metalloids
made if the remaining elements. Properties inbetween the orher groups, they are all solids at room temperature. They conduct electricity, but not very well, and so are called semi-conductors. Most are shiny and gray, and are brittle.
patterns in the periodic table
all elements in the same column have similar physical and chemical properties.
Alkali metals (group 1)
soft, want to give away one electron, reactivity increases as you go down, most reactive metals (especially with water), 1 valence electron, francium is the most reactive metal.
alkaline earth metals (group 2)
denser, hugher melting points than group 1, conducts electricity well, fairly reactive but not as much as group 1, 2 valence electrons, reactivity increases as you go down
transition metals (groups 3-12)
all are metals (shiny, hard, lustrous), most are found combined with other elements in ores, mercury is the inly liquid metal at room temperature
Pnictogens (group 15)
metals, nonmetals, and metalloids. Reactive, bonds with other elements by sharing electrons, useful to living thing in small amounts; deadly in large amounts. 5 valence electrons (need 3 more), reactivity decreases as you go down
Chalcogens (group 16)
non-metals and metalloids, oxygen and sulfur are essential for life; selenium conducts electricity when exposed to light, very reactive, 6 valence electrons (gains 2), reactivity decreases as you go down
halogens (group 17)
non-metals (except for astantine), halogens means "salt former," has 7 valence electrons (gains 1), reactivity decreases as you go down, most reactive non-metals, fluorine is the most reactive
noble gases (group 18)
non-metals, inert (dont react with other elements), used in types of lighting, 8 valence electrons
protons (p+)
positive charge, located in nucleus, 1 amu (atomic mass unit), determines identity of the element, atomic number
neutrons (n0)
neutral charge, located in nucleus, 1 amu (atomic mass unit), supplies proper mass to hold nucleus together, mass # - atomic #
electrons (e-)
negative charge, located in obritals around the nucleus, 2000x smaller, determines bonding and how it reacts, same as # of protons
rows
called periods, tells the number of obritals
columns
called families or groups, elements in the same column have similar chemical properties, tells the number of valence electrons based on the group number
element
a pure substance made of only one type of atom
molecule
a substance that has two it more elements bonded together
compound
a substance that had two or more different elements bonded together
ionic compound
a compound composed of ions (atoms with a charge, lost or gained an electron), which are held together through ionic bonding
molecular compound
a compound formed when atoms of two or more different elements share electrons creating a covalent bond, usually formed between 2 or more non1metals and are also called covalent compounds
ionic vs molecular
Ionic: opposite charges attract, transfer of electron, metal to non metal, lattice structure (solids)
molecular: atoms share electrons to complete valence shells, non metal to non metal, smaller compounds with 2-3 atoms linked
colvalent bond
a bind that results from the sharing if outer electrons between non-metal atoms to form a molecule
diatomic molecule (HOFBrINCl)
molecule that has only two atoms (Hydrogen, Oxygen, Fluorine, Bromine, Iodine, Nitrogen, Chlorine)
Signs of a chemical change
bubbles are formed, change in colour, hard to reverse, a solid is formed, and light/heat is being produced - change in energy