Atom – fundamental unit of matter
Proton – positive charge, in nucleus, 1 amu
Neutron – neutral, in nucleus, 1 amu
Electron – negative charge, around nucleus, 0 amu
All mass of atom in small dense nucleus
Most of atom is empty space where electrons fly around
Electrons attracted by protons
Nucleus is all positive charge but does not break apart
Nuclear force – strong force that holds nucleus together, only works over short distance
Number of protons = number of electrons
Ion – different number of electrons than protons
More electrons – negative ion = anion
Less electrons – positive ion = cation
Isotope – different number of neutrons than protons
Electrons – fill energy levels around nucleus (innermost first)
Energy levels have orbitals where electrons are found
Level 1 = s = 2 electrons
Level 2 = s p = 8 electrons
Level 3 = s p d = 18 electrons
Level 4 = s p d f = 32 electrons
Each orbital can hold certain number of electrons:
s = 2 electrons p = 6 d = 10 f = 14
Electrons will pair up when they fill orbitals
Orbital configuration = 1s 2s 2p 3s 3p 4s 3d 4p 5s 4d 5p 6s
Periodic Table
Arranged by atomic number – number of protons
Patterns of table:
Ionization energy (energy needed to lose electrons) increases as you go left to right, decreases as you go down
Electronegativity (ability to attract electrons) increases as you go left to right, decreases as you go down
Atomic size decreases as you go left to right, increases as you go down (more protons as you go across and down so more attraction to center)
Metallic Properties – decrease as you go across, increase as you go down
Valence electrons – increase as you go across 1-8 (skip transition metals)
3 groups
1. metals
- shiny solids - high melting and boiling points
- large atomic radius - low ionization energy
- lose electrons - malleable – hammered into shapes
- ductile – drawn into wire - conduct heat / electricity
2. nonmetals
- dull, brittle - poor conductors of heat / electricity
- gain electrons
3. metalloids – exhibit characteristics of metals and nonmetals
-properties based on location on periodic table
Families on Table
Alkali metals – group 1, 1 valence electron, soft shiny metal, reactive
Alkaline Earth metal – group 2, 2 valence electrons, shiny, reactive
Transition metals – middle block, 1 or 2 valence electrons, strong, not
reactive
Halogens – group 17, 7 valence electrons, nonmetals, reactive
Noble Gases – group 18, 8 valence electrons, stable (full valence)