Transcript chapters 1-4

Anything that occupies space and has mass is matter.
laws
observation
hypothesis
experiment
theory
Bias- a strong preference that
inhibits impartial judgment.
Physical properties
Physical changes
- reversible, no new subst.
Mixtures can be separated by certain physical method(s).
Chemical properties
Chemical changes
- irreversible, different
substances
Measurement never gives exact value, contains all
known figures plus one estimated.
Significant figures
Rounding
Math – mult/div: #sig.figs
- add/subt.: uncertainty
Scientific notation: A x 10X
A: gives # sig.figs
X: exponent (whole #)
State
Solid
Liquid
Gas
Shape
Definite
Indefinite
Indefinite
Known: 2
Estimated: 5
 2.5
Volume
Definite
Definite
Indefinite
Compress.
V.Slight
Slight
High
Known: 2.5
Estimated: 0
 2.50
SI system
Physical quantity
Length
Mass
Time
Temperature
Amount of subst.
Name
Abbrev.
meter
m
kilogram kg
second
s
Kelvin
K
mole
mol
Density: extensive property (does not
depend on the amount of sample
d = m/V
m=dxV
Elements and compounds
Elements
Distribution:
Atoms and molecules:
Greek Prefix
kilo- (k)
mega- (M)
giga- (G)
tera- (T)
Meaning
one-trillionth (10-12)
one-billionth (10-9)
one-millionth (10-6)
one-thousandth (10-3)
one-hundredth (10-2)
one-tenth (10-1)
Meaning
one thousand (103)
one million (106)
one billion (109)
one trillion (1012)
~100 elements, millions of compounds
H and He most abundant in space, O and Si in earth
crust, O and C in human bodies.
Atom – smallest building block; molecule – combination of
two or more atoms. Can be an element or compound.
one or two letters, first capitalized.
Most elements, metallic luster, heat/electric conductivity,
malleable, ductile, high melt/boil. points and density.
Symbols:
Metals
Nonmetals:
V = m/d
Greek Prefix
pico- (p)
nano- (n)
micro- (m)
milli- (m)
centi- (c)
deci- (d)
17 elements,
Opposite
Metalloids: 7 elements,
intermediate
Hydrogen – group of its own
Periodic table: symbol, atomic number; elements organized in groups (e.g. noble gases, noble metals)
Diatomic molecules exist as natural state of seven elements (all nonmetals).
A compound is a distinct substance that contains two or more
elements combined in a definite proportion by weight.
Compounds can be decomposed chemically into simpler
substances – that is, into simpler compounds or elements.
H2O: molecular
NaCl: ionic
Molecular: covalent bonds
Ionic: no bonds, electrostatic forces.
Chemical formulas: name of compound,
names of elements, how many element of
each kind, atomic ratio. Does not specify
arrangement of atoms.
Ba3(PO4)2
Chemical reaction: reactant(s) – yield – product(s)
Conservation of mass – total mass of reactants
equals to the total mass of products.
Heat: one form of energy. Its measure is temperature.
Conservation of energy: energy only changes
forms, cannot be created/destroyed.
q = m C Dt
Joules


C in 

o
 gram Celcius 
Problem 4: What is the final temperature of a 20.0 g block of iron after it has absorbed 100.0 J
of heat, if its initial temperature was 25.0 oC? Hint: solve for Dt, then add it to the initial temp!
Dt =
Q
mC
100.0 J
=
J
20.0 g x 0.449 g oC
= 11.1 oC
 Final temp. = 25.0 oC + 11.1 oC = 36.1 oC