PS test 2 Flashcards
Atoms
mostly empty space, majority of mass due to protons and neutrons in neucleus. electrrons in cloud about nucleus of atom.
Electron
(-1) charge (1/18*1 weight of proton) determines chemical properties.
Proton
(+1) charge, number of protons (atomic number) determines the identity of element
Neutron
(0) charge, number of neutrons determines which isotope
Atomic Weight
averaged massed of isotopes of element.
Mole
weight in grams of AVAGADRO’S NUMBER of particals
Periodic Law
properties of elements periodically repeat when elements are arranged in order of atomic numbers.
Metal
form (+) ions, form bases with OH, shiny, malleable, good electrical ex of base Fe(OH)2
Non-Metals
form (-1) ions, forms acids with H+, ex. HCI, dull luster, brittle, poor electrical conductors except for graphite.
Inert Gases
unreactive chemically, gases, other elements try to obtain same electron arrangement.
Group or family
column on the periodic chart with similar properties due to same number of outermost electrons (valence elecctrons) periodic chart is based upon periodic law and (organizes and predicts properties)
electronegitivity
Measure of attraction of an element for electrons. Max electroneitivity is Fluorione, F with 4.0, 1/2 difference 1.7, min electronegativity is francium, Fr with 0.70 equals or exceeds. if difference between electronegativities of two elements exceeds 1.7, bond is ionic.
Example : Na2O
electronegativity O = 3.44
electronegativity Na = 0.93
3.44-0.93= a difference of 2.51, this exceeds 1.7, so Na- O bond is ionic
Ionic Bond (Na+Cl-1)
attraction between ions opposite charge bonds elements
Activation Energy
engergy necessary to start a chemical reaction. Ex. striking a match, paper burning, ect.
ion changes
- metal > take group number and make +, Ex: Sn Metal group IV is Sn^+4
- nonmetal > Group Number - 8 = charge, Ex C non-metal group IV is C^-4
chemical change
new substance formed Ex: H2(gas)+ 1/2 O2(gas)= H2O, burning paper gives CO2 + Carbon + Water which is not paper but new substances.
physical change
different form, but same substance: water to ice, breaking a rock, tearing paper still is paper.
oxidation
occurs same time as reduction, raises charge by removing negative electrons.
Rate of chemical reaction depends upon
- Concentration of chemicals
- Temperature (speed of molecules)
- Catalyst
- Type Bonds
colllision theory of chemical reactions
- molecules must collide to react more collisions= faster
A. greater concentrations means more collisions
B. smaller solid particals means more collisions - molecules must be oriented correctly to react.
A. catalysts orient molecules correctly - speed of molecules increases as temperature increases= faster
salt
is crystalline compound formed in acid/base reaction.
catalyst
changes speed of reaction, but is not used up in reaction. it changes speed by changing activation energy
law of definite composition composition (proportions)
the % of an element in a compound is fixed. Calculation of weight of a mole/atomic weight/ moleculer weight of Ca(HCO3)2
1 * Ca = 1 * 40 = 40
2 * H = 2 * 1 =2
2 * C = 2 * 12 = 24
6 * O = 6 * 16 = 96/162 grams
Equilibrium
equal rates of reaction in both directions directions and constant temperature.
