chemistry fall final exam review

10th

macroscopic

realm of things large enough to be observed by the human senses

microscopic

realm we cannot see directly

scientific method

1. identify a problem
2. create a hypothesis
3. experiment to test the hypothesis
4. collect and analyze data

pure research

conducted to gain knowledge for the sake of knowledge itself

applied research

solve specific problems

technology

application of scientific problems

kilo

1000

hecto

100

deca

10

base

1

deci

-10

centi

-100

milli

-1000

King Henry Died By Drinking Chocolate Milk

\- to convert to a larger unit, move decimal left or divide

\- to convert to a smaller unit, move decimal right or multiply

scientific notation to decimal notation

\- positive exponent, move decimal right to create a bigger number

\- negative exponent, move decimal left to create a smaller number

decimal notation to scientific notation

move decimal so the coefficient is between 1 and 10.

\- if the number was

accuracy

how close the measured value is to the actual value

precision

how close the measurements are to each other

percent error

| experimemental-accepted | /accepted x 100

non zeros

always counted

leading zeros

never counted

captive zeros

always counted

trailing zeros

only counted when comes after a decimal

scientific notation

only coefficient is counted

multiplying/dividing

answer has the least number of sig figs in the original data

adding/subtracting

answer has the least decimal places as the original data (numbers in front of the decimal can stay)

nucleus

\- accounts for atom's mass

\- composed of nucleons (protons and neutrons)

\- dense center

electron cloud/energy level/shell

\- outside of the nucleus where the electrons are located

\- accounts for atom's volume

atomic number (Z)

protons and electrons

ion

when an atom loses or gains electrons

anion

\- negative ion

\- when an atom gains electrons

cation

\- positive ion

\- when an atom loses electrons

mass number (A)

protons+neutrons

neutrons

mass-atomic number

isotopes

same number of protons, different number of neutrons, therefore different mass

average atomic mass

sum of (mass x abundance)

strong nuclear force

\- holds the nucleus together

\- short range force of attraction

electrical forces

\- between the positively charged protons

\- long range force of repulsion

chemical reactions

involved the valence electrons; the identity of the elements is unchanged; obeys the law of conservation of mass

nuclear reactions

involved the atom's nucleus; elements involved may change into new elements in a process called transmutation; mass may be converted into energy and unstable nuclei lose energy in a process called radioactive decay

unstable nucleus

\- electrical force overpowers the strong nuclear force

\- wrong neutron:proton ratio (higher the ratio, the more radioactive- atomic #>82

alpha particle

use paper to block (weakest)

\- mass: decreases 4

\- atomic #: decreases 2

beta particle

use tin foil to block

\- mass: unchanged

\- atomic #: increases 1

gamma decay

use thick lead and concrete to block (strongest)

\- mass: unchanged

\- atomic #: unchanged

nuclear fission

breaking of a large nucleus into smaller pieces

nuclear fusion

a small nuclei fusing into a bigger nuclei

coulomb's law

F= # of protons/distance

\- the more protons, the more force, resulting in a smaller atom

\- the greater the distance, the less force, resulting in a larger atom

wavelength

distance between two repeating points on a wave

frequency

number of waves that pass a given point in a second. measured in seconds/hertz/s-1

speed of light

c=λv

radio

\- low frequency

\- high wavelength

gamma

\- high frequency

\- low wavelength

plank's equation

E=hv

s shell

\- 1 orbital

\- 2 electrons

\- sphere shape

p shell

\- 3 orbitals

\- 6 electrons

\- dumbbell shape

d shell

\- 5 orbitals

\- 10 electrons

\- clover shape

f shell

\- 7 orbitals

\- 14 electrons

\- complicated shape

pauli's exclusion principal

electrons in an orbital must have different spins (+1/2 or -1/2)

quantum numbers

n- group #

l- special code (s=0; p=1; d=2; f=3)

m- orbital place (0 in the middle, dependent on special code)

s- spin # (+1/2 or -1/2)

aufbau rule

lowest energy orbitals are filled first

hund's rule

all orbitals must have an electron before pairing

metals

left side of stair case except for hydrogen. shiny, malleable, good conductors

non-metals

right side of staircase. dull, brittle, poor conductors

metaloids/semi-metals

elements that touch the staircase except for aluminium. conductors or insulators depending on the environment

atomic radius

\- decreases across period

\- increases down group

ionic radius

\- decreases across period

\- increases down group

ionization energy

\- increases across period

\- decreases down group

electronegativity

\- increases across period

\- decreases down group(highest at fluorine, lowest at francium)

metal reactivity

increases from right to left

non-metals reactivity

increases from left to right

octet rule

atoms transfer or share electrons in order to acquire a full outer electron shell just like noble gases

properties of ionic compounds

crystalline solid structure at room temperature, high melting and boiling points, soluble in water, does not conduct electricity as solid but has electrolytes

delocalized electrons

electrons that do not belong to one nucleus or atom. they are shared and can freely move. properties: good conductors, luster, malleable, ductile, crystal solids

alloy

solution of two or more metals (intersticial and substitutional)

intersticial

space between larger metal atoms are filled with smaller atoms

substitutional

atoms in original metallic solid are substituted/replaced with other metals of similar atomic size

bond order

number of bonds between two atoms

\- shorter the bond length, stronger the bond

\- higher the bond order, stronger the bond

\- bonds broken: energy absorbed

\- bonds formed: energy released

endothermic reactions

energy required to break bonds is greater than energy released. energy is absorbed

exothermic reactions

more energy is released when forming than required to break. energy is released

properties of covalent compounds

weak forces of attraction, low melting and boiling points, volatile liquids (evaporates easily), does not conduct electricity

lewis structures

\- central atom is the least electronegative (never fluorine or hydrogen; always carbon when present)

\- find available electrons: count valence electrons

\- find required electrons: give octets and 2 for hydrogen

\- find shared electrons: subtract available from required

\- find bonds: divide the shared electrons by 2

\- check: electrons = electrons available

\- polyatomic ions: place inside brackets with net charge

max number of bonds (HONC)

1- hydrogen/halogens

2- oxygen

3- nitrogen

4- carbon

polar

electrons are being shared unequally, creating a pull of negative and positive ends. the negative end is the atom that is more electronegative (H2O is polar)

non polar

electrons are shared equally, thus no positive or negative ends (CH is always non polar)

covalent bonds difference in electronegativity

\- greater than 0.4 -> polar

\- less than or equal to 0.4 -> non polar

VSPER theorgy

three dimensional shapes created by electrons repelling each other

finding charge clouds

each bond is always counted as 1 cloud. any lone pairs are counted as 1 cloud. maximum is 4

2 charge clouds

\- geometry of electrons: linear

\- molecular geometry: linear

\- 180

3 charge clouds

\- geometry of electrons: trigonal planar

\- molecular geometry: trigonal planar or bent/angular

\- 120

4 charge clouds

\- geometry of electrons: trigonal planar

\- molecular geometry: tetrahedral, trigonal pyramidal, bent/angular

\- 109.5

trigonal planar

replace 1 bond with lone pairs

tetrahedral

flat (bonds on all 4 sides)

bent/angular

2 bonds, 2 lone pairs

hybridization

\- 2 clouds: sp

\- 3 clouds: sp2

\- 4 clouds: sp3

always polar

bent/angular and trigonal pyramidal

nonpolar

same atoms surround central atom

polar

different atoms surround central atom and lone pairs

dipole-dipole

positive end is attracted to negative ends of polar bonds

hydrogen bond

stronger type of dipole-dipole. only works if hydrogen is connected to FON

london dispersion forces

nonpolar intermolecular force