final Flashcards
commonly used prefixes in metric system
prefix symbol meaning power of 10
mega M 1,000,000 10^6
kilo k 1000 10^3
deci d 0.1 10^-1
centi c 0.01 10^-2
milli m 0.001 10^-3
micro μ 0.000001 10^-6
nano n 0.000000001 10^-9
rules for sig figs
1) all nonzero integers ALWAYS count for significance ex: 3456 has 4 sig figs
2) zeros (3 classes of zeros)
a) leading zeros:NEVER count as sig figs
ex: 0.048 has 2 sig figs
b) captive zeros: ALWAYS count as sig figs ex: 16.07 has 4 sig figs
c) trailing zeros: only significant when # HAS A DECIMAL POINT
ex: 9.300 has 4 sig figs; 0.004020 has 4 sig figs; 150 has 2 sig figs
sig figs for x and ÷
the # of sig figs for answer is LEAST amount of sig figs u have in the problem
ex: 1.342 x 5.5 = 7.4
* when solving many calculations for 1 problem, don’t convert sig figs until LAST STEP
sig figs for + and -
only count decimal places
ex: 23.445 + 7.83 = 31.275 = 31.28
ex: 101 + 1.0 = 102
- always solve from left to right
density
density =mass/volume or D=m/V
- mass of substance per unit volume of substance
- common units: g/mL or g/cm^3
- when mass increases, density increases (directly proportional)
- when mass is constant and volume decreases, density increases (inversely proportional)
physical properties
- characteristic that are directly observable and unique to a substance
- ex: odor, volume, color, state (s,l,g,p), density, boiling pt, melting pt
chemical properties
- a substance’s ability to make new substances
- characteristics that determine how the composition of matter changes as a result of contact w/ other matter/influence of e
- characteristics that describe behavior of matter
- ex: flammability, rusting of steel, toxicity, enthalpy, chemical stability, reactivity, digestion of food
ethyl alcohol at 78ºC boiling point is a __ property
physical
hardness of a rock is a __ property
physical
sugar fermenting to form ethyl alcohol is a __ property
chemical
physical change
- change in 1 or more properties of a substance and not in its chemical composition
- ex: boiling pt or freezing water
- 3 states of water: in all phases, water mols are still intact; motion of mols and distance between them change
chemical change
- given substance becomes a new substance w/ diff properties and diff composition
- ex: Bunsen burner, methane reacts w/O2 to make CO2 and H2O, baking a cake, bleaching teeth (rxn happening), digesting food
crushing salt is a __ change
physical
burning wood is a __ change
chemical
dissolving sugar in water is a __ change
physical
melting a popsicle is a __ change
physical
protons and neutrons have the same __
mass
why do diff atoms have diff chemical properties?
the chemistry of an atom arises from its e-
isotopes
diff # of neutrons
- atoms w/ the same # of protons but diff # of neutrons
- show almost identical chem. properties
- chemistry of an atom is due to its e-
- in nature, elements are usually found as a mixture of isotopes
isotope symbol
A X Z X= the chemical symbol of element A= mass # (# of protons + # of neutrons) Z= atomic # (# of protons)
groups/families
elements in same VERTICAL columns and have similar chemical properties
periods
HORIZONTAL rows of elements
metals
LEFT of staircase
-most elements are these
non-metals
RIGHT of staircase