solid
fixed shape and volume, particles touching, not moving
liquid
fixed volume, unfixed shape, particles touching and moving a little
gas
no fixed volume or shape, particles far apart and moving a lot, not charged
plasma
no fixed volume or shape, particles far apart and moving a lot, charged
physical property
anything you can see without changing the substance
physical property ex.
transparency, boiling point, density, elasticity, malleability, brittleness, melting point
chemical property
you can only see by changing the substance
chemical property ex.
flammability, ability to rust, reactivity with vinegar
physical change? (is it reversible?)
when the identity of the substance doesn’t change (reversible)
physical change ex.
shattering, melting, separating (sand from gravel), dissolving, mixing, evaporating
Chemical change
when the identity of the substance changes (irreversible), during a chemical reaction
Chemical change ex.
rusting, bleaching, cooking, burning, exploding
extensive property
depends on how much matter there is
extensive property ex.
mass, weight, volume
intensive property
doesn’t matter how much matter there is
intensive property ex.
color, combustibility, density, melting point, malleability
5 signs of a chemical reaction
formation of a gas
color change/ emission of light
odor change
temp change
formation of a precipitate
parts of a chemical reaction
reactant, yield arrow, product
Law of conservation of mass
in a closed system, mass cannot be created or destroyed
the 2 classifications of matter
pure substances and mixtures
pure substance
only one type of molecule, ex. water or carbon
compound
a molecule made of different atoms, ex H20 (water)
can be broken down into molecules using chemical charges
compounds can be molecular, ionic, or intermetallic
element (define, examples)
an atom with specific characteristics, ex. hydrogen, iron, copper
can be metals or nonmetals, can’t be broken down further
mixture
a combo of 2 substances, not chemically bonded
can be solutions or heterogeneous mixtures
CAN be separated physically
solution (aka homogenous) (how are the molecules distributed? example?)
group of molecules that are evenly distributed, ex. gasoline, air, soda
heterogeneous mixture
a solution (group of molecules) that is unevenly distributed, ex. salad dressing
accuracy
“the extent to which a measurement approaches the true value of a quantity “
how correct is it?
precision
“the extent to which a series of measurements of the same quantity made in the same way agree with each other, not necessarily accurate.”
how close together are your answers? (they don’t have to be right)
percent error formula
[(experimental - accepted) / accepted] * 100
mass
the amount of matter an object contains. Doesn’t change unless you add/remove matter
find with a balance, use grams
volume (define, what units?)
the amount of space an object occupies
find with liquid or a ruler, use mL for liquids or cm³ for solids or L for gases
density (define)
The compactness of the molecules or particles of a substance
more compact molecules = greater density
density formula
mass/ volume
remember:
mL – volume
g – mass
g/mL org/cm³ org/L- density
billiards ball atomic model
small, hard sphere
created by dalton in 1808
plum pudding atomic model (what? when? who?)
negative electrons in a positive atom
created by thompson in the 1890s
nuclear model (what? who?)
nucleus with electron shell
created by rutherford around 1911
modern atomic model (who? what?)
discovered neutrons, current model used today
created by chadwick around 1932
atom
the smallest particle of an element that still has the chemical properties of the element
nucleus
very small thing in the center of the atom
made of at least one proton (p+) and usually at least 1 neutron (n*)
surrounding the nucleus is a cloud of electrons (e-)
protons (p+) (define)
located in nucleus, positive charge, big and heavy
neutrons (n*)
located in nucleus, no charge, big and heavy
electrons (e-)
outside the nucleus, negative charge, tiny and light
isotopes
2 atoms with different # of neutrons
have the same atomic #, different mass #s
protons never change
neutrons can change
ions
an atom with a charge, # of electrons change
if atom loses electrons, atom is + and (vice versa)
protons, neutrons, atomic # and atomic mass stay the same
1st periodic table
created by Dmitri Mendeleev, 1869
Elements arranged:
Groups had similar properties
Increasing atomic mass
Spaces left for undiscovered elements
current periodic table
created by Henry Mosely, 1913
Elements arranged:
By atomic #, not mass
You already know what it looks like
periodic law
“When elements are arranged by increasing atomic #, there is a periodic repetition of physical and chemical properties.”
Or in simple words: when you put elements in order by atomic #, you can see some patterns.
what’s the only metal that’s liquid at room temp
mercury
the most reactive element groups
alkaline metals, then alkaline earth metals cause they only have 1 valance electron
what are the most reactive nonmetals
halogens
what do noble gases (except helium) bond with
nothing
metals (where? describe)
left side of stairsteps
In the A block
conduct heat, electricity
high luster, solid at room temperature (not mercury)
ductile, can be made into wire
malleable, can be made into a sheet
nonmetals (where? describe, example)
right side of stairsteps
In the A block
Most are gases at room temperature (not bromine, it’s a liquid)
Poor conductors, brittle, dull
ex. chlorine and oxygen
metalloids
along stairsteps
In the A block
Properties of metals and nonmetals
Conductors and insulators
Ex. Semiconductors are Selenium, Germanium, arsenide
catalyst
the thing on top of the yield arrow, speeds up a chemical reaction
dalton
(what model? what discoveries?)
discovered the atom, did billliards ball model
thompson
discovered electrons, did cathode ray tube and plum pudding
rutherford
what experiment? what discoveries?
nucleus, protons on nucleus, discovered that the atom is mostly empty space…………
nuclear model (nucleus with electron shell)…………
gold foil experiment
bohr (discoveries? models?)
atomic energy levels, atomic model, planetary model.
electrons shell is made of orbits/shells
heisenberg and schroedinger (created, discovered?)
electron cloud and orbitals, heisenberg uncertainty principle, quantum model
hyphen notation
(element name) dash (mass number)
ex. uranium-235
isotope notation (nuclear symbol)
top - mass # bottom - atomic #
ex. U²³⁵₉₂ (pretend like that’s lined up)
atomic number =
# protons (# electrons if neutral)
mass number =
protons + neutrons
atomic mass =
the decimal in the element box
neutrons =
mass # - atomic #
reactivity
⇙ How easily an element reacts with other elements ⇙
ion
an electron with a charge
shielding effect
when the inner shells shield the outer shells from the nucleus’s pull
metallic character
⇙ how metallic it is ⇙
atomic radius
⇙ how big the atom is ⇙
ionization energy
⇗ amount of energy required to remove an electron from the valance shell ⇗
electronegativity
⇗ how attractive an atom is ⇗ smaller atoms have higher attractivity
cation
positive, lost electrons, smaller than neutral, metal
anion
negative, gained electrons, larger than neutral
ex. iodide, chloride, hydroxide
octet rule
usually there’s 8 electrons in a valance shell
ionic compounds
metal, nonmetal
when an electron is taken from another atom
molecular (covalent) compounds
(what are they made of, what process?)
nonmetal, nonmetal
when electrons are shared between atoms