chem test 4 Flashcards
nuclear reactions
reaction that affects the nucleus of an atom
nuclear fission
heavy nucleus splits into more stable nuclei, occurs in bombs/reactors, low mass combines to form more stable and heavier atom, happens in stars
chain reactions
starting material is made as product so reaction continues to happen
alpha
particle w/ 2 protons and 2 neutrons bound together and had positive charge. similar to helium. lowest penetrating abilities. 4/2He and 4/2a.
beta
an electron. more power than alpha. has negative charge. 0/-1B or 0/-1e.
positron (beta positive)
positivity charged beta particle. 0/+1e
neutron
has symbol 1/0n
gamma y
no mass and no charge. js energy. highest penetrating power. 0/0y
balancing nuclear reactions
mass number and atomic numbers on each side must be equal.
what radiation has the greatest penetrating power?
gamma
least penetrating power to the greatest penetrating power
alpha particle, gamma ray, beta particle
in order of increasing mass
electron → proton → alpha particle
What is the mass number of an alpha particle?
4
Which of the following particles has the least mass
beta
Which nuclear emission has no charge and no mass
gamma
Which nuclear emission has the greatest mass
alpha
Which type of radiation is identical in mass and charge to a helium nucleus
alpha
Which particle has the greatest mass?
alpha
Which nuclear decay emission consists of energy, only?
gamma
Artificial transmutation is brought about by using accelerated particles to bombard an atom’s
nucleus
A beta particle may be spontaneously emitted from
an unstable nucleus
A change in the nucleus of an atom that converts the atom from one element to another element is called
transmutation
Alpha particles and beta particles differ in
D) both mass and charge
What is the name of the process in which the
nucleus of an atom of one element is changed into
the nucleus of an atom of a different element?
transmutation
Which of these types of nuclear radiation has the
greatest penetrating power?
gamma
radioactive
nucleus will spontaneously decompose
alpha decay
alpha particle is created
beta decay/beta negative/electron emission
beta particle is created
positron decay/beta positive emission
positron is created
nuclear decay occurs bc the nucleus of the atom is
unstable in current form/radioactive
the nucleus will proceed to transmutate until it is
nonradioactive
decay can happen in _ steps. each step can be different type of decay, or take different amount of time bc each has its own half life
one or many
half life
time required for half of og sample of nuclei to decay
periodic
repeatable pattern
atomic radius
size of atom, or how far the electrons are from the nucleus
how does atomic radius change
down + left +
biggest atomic radius element
francium
smallest atomic radius element
fluorine
why does atomic radius size decrease as you move to the right and increase as u move down?
down = more electron shells and bigger radius
right = less protons so less electrons in nucleus
electronegativity
ability of the atom to attract electrons when in a bond with another atom
most electronegative element
fluorine
least electronegative element
francium
how does electronegativity change
up + right +
y is fluorine better at attracting the electrons than francium?
the smaller an atom, the closer its electrons are to the nucleus. they are more attracted the closer they are to the nucleus, and vis versa
ionization energy
energy needed to lose one electron (creating a cation)
how does ionizing energy increase
up + right +
highest ionizing energy element (hard to lose electron)
fluorine
lowest ionizing energy element (ez to lose electron)
francium
why is it so easy for Francium to lose an electron and so hard for Fluorine to lose an electron?
fluorine is the smallest, meaning the electrons are closer to the nucleus and harder to get away, and vis versa
VSEPR
valence shell electron pair repulsion
electron pairs around a central atom will…
get as far apart from each other as possible
tetrahedral
4 surrounding atoms. 0 lone pairs. bond angle 109.5*. AB4
linear
180* AB2. 2 atoms are bonded together, or 2 surrounding atoms and 0 lone pairs are bonded.
trigonal planar
3 surrounding atoms and 0 lone pairs. bond angle 120*. AB3
trigonal pyramidal
3 surrounding atoms and 1 lone pair. <109.5*. AB3E
bent or angular
2 surrounding atoms and 1 or 2 lone pairs. <120* if 1 lone pair or much less than 109.5* if 2 lone pairs. AB2E or AB2E2
polarity
2 poles
whats a pole
poles of a magnet or two sides of different charge
what does it mean if a molecule is polar
one region of the molecule has a positive charge, and another has a negative charge (separation of charge)
how do we create polartiy
when electrons are shared unequally in a covalent (2 non metals) bond. (electrons are attracted to one atom instead of another)
how do we know which atom the electrons are attracted to in polarity?
look at the electronegativity of the atoms
in order to find if a bond is polar, look at the difference between the _ of the two atoms
electronegativity
non-polar covalent
<0.3 and equal sharing
polar covalent
0.3<x<1.7, unequal sharing
ionic
<1.7 en
how do u know if a molecule is polar?
draw lewis dot and look at the shape. draw arrows facing more electronegative atoms.
dipole movement
a measure of how unequal the distribution of electric charge is in a molecule
if arrows point in same direction in dipole movement…
they are additive and all electrons move to that side, and we create different charged areas (polar!)
if arrows point in opposite direction… (away or towards each other)
cancel each other out, the electrons are equally moved around and we have the same charge everywhere (nonpolar!)
state of matter: solid
molecules are close, locked in place, vibrate, and crystalized in place
types of crystalline structures
ionic solid, molecular solid, atomic solid
ionic solid
crystal is made of separate ions and is a repeating pattern of positive and negative ions
molecular soild
crystal is made of individual molecules that bond together
atomic solid
crystal is made of individual atoms that bond together
liquid
molecules are close but can move. they r not stuck together well, and can escape to gas phase (vapor pressure)
Solid
molecules are very close connected, and locked in place and can only vibrate to move. they usually form a very specific structure called crystalline solid. (crystalized in place)
crystalline structures types
ionic solid, molecular solid, atomic solid
ionic solid
the crystal is made of separate ions, and is a repeating pattern of positive and negative ions
molecular solid
the crystal is made of individual molecules that bond together
atomic solid
the crystal is made of individual atoms that bond together
liquids
molecules are still close to each other but now have more freedom to move. they are not as stuck as solids, and can escape to gas phase (vapor pressure)
gases
molecules are completely separate and have ultimate freedom to move around. they are independent of each other, and have many properties
intermolecular forces
the forces that connect and separate molecule of a substance together
the stronger intermolecular forces are, the harder it is to…
separate the molecules
ionic intermolecular force
opposite charges on magnets pull on each other
hydrogen bonding intermolecular force
hydrogen + F, N, or O
dipole dipole bonding intermolecular force
polar / non even
(one molecule is positive and one is negative)
london dispersion bonding intermolecular force
non polar / even
(not all molecules have dipole)
polarity
lewis dot. draw arrows toward more electronegative element, to represent the direction the electrons are moving
dipole
the arrangement of charges of a molecule. + -. the force between N and S
if dipole arrows point in the same direction…
they are additive. all electrons move the the same side and different charges are created (polar)
if dipole arrows point in different directions (towards or away from each other)…
they cancel each other out and the electrons are equally have the same charge everywhere (non polar)
polarity
the property when there are two poles
what is a pole
poles of a magnet or two sides of different charge
for a molecule to be polar…
one side has to have a positive charge and the other negative (separation of charges)
how do we create polarity?
when electrons are shared unequally in a covalent bond. the electrons are attracted to one atom more than the other
how do we know which atom the electrons are more attracted to?
the more electronegative one
non-polar covalent bond
equal sharing; en<0.3
polar covalent
unequal sharing; 0.3<en<1.7
ionic
1.7<en
VSEPR
valence shell electron pair repulsion
linear
- 2 atoms 180* AB2
- 2 surrounding atoms (3 total) 0 lone pairs 180*
trigonal planar
3 surrounding atoms, 120*, AB3, 0 lone pairs
tetrahedral
4 surrounding atoms, 0 lone pairs, 109.5*, AB4
trigonal pyramidal
3 surrounding atoms, 1 lone pair, <109.5*, AB3E
bent/angular
2 surrounding atoms, 1 or 2 lone pairs
- 1 LP = <120* and AB2E
- 2 LP = <109.5* and AB2E2
what does phase diagram show
how pressure and temperature affect the 3 phases of matter
triple point
a point where all 3 phases intersect, solid, liquid, and gas exist at same time
critical point
liquid and gas coexist in new type of fluid called supercritical fluid
melting
solid to liquid
freezing
liquid to solid
vaporizing
liquid to gas
condensation
gas to liquid
sublimation
solid to gas
deposition
gas to solid
joule
standard unit of measurement for energy
caloire
amount of energy required to raise temp of 1 gram of water by 1*C
how many cal is 1 J
1 cal = 4.184 J
potential/stored energy
the energy that is bonding atoms and molecules togeether
if energy is released…
there is less energy stored in the chemical bonds
if energy is absorbed…
more energy is stored in the bonds
evaporation
molecules at surface of liquid are able to break free of their forces and turn into gas molecules
boiling
molecules inside liquid stare can separate and turn into gas molecules
specific heat capacity
amount of energy required to change the temp of 1 gram of substance by 1*C, and is different for each substance and the state of matter
heat curve
shows us how a substance is changing phase over time compared to the temperature change, shows what temp a phase change occurs
temperature is related to kinetic energy… meaning
the faster a molecule moves, the higher the kinetic energy/temp
pressure
force exerted over an area
barometer
used to measure pressure from the atmosphere. its filled with mercury
how does a gas apply force?
the force is when a molecule collides with the side of a container
what are the gas laws
a way to relate pressure, volume, and temp of a gas. describes how if u change one variable, it will affect the other variables and allow u to see changes in them
temperature definition
how fast particles move
pressure definition
how often particles collide with container
volume definition
how much space particles take up
boyles law
there’s a connection between pressure and volume. they are inversely related, so if u increase one the other will decrease
charles law
there is a connection btwn volume and temp. they are directly related, so if u increase one then the other will also increase
directly related meaning
if u increase one factor, the other will also increase
inversely related meaning
if u increase one part, the other will decrease
gay lussac’s law
there is a connection btwn pressure and temp. pressure and temp are directly related. one increase the other increase
combined gas law
pressure(1) x volume(1) / temp(1) = pressure(1) x volume(2) / temp(2)
more pressure means ___ collisions
more collisions
less volume means __ pressure
more pressure
more temp means ___ particles
faster particles
faster particles means __ volume and _ collisions
more volume/less collisions
more movement means __ temp
higher temp
what is temperature?
how fast particles are moving
can temperature be negative?
no
absolute scale
a scale in which numbers can only be positive
what is the absolute scale for temperature?
kelvin scale
whats the lowest temperature possible?
zero kelvin
if temperature is zero, particles are…
no longer moving (hard to achieve, and no experiment has EVER done it)
avogadro’s law:
there is a connection between volume and number of moles of a gas.
more moles = __ space
more space
if moles increase, volume _
increases
number of moles and volume are ___ related
directly related (one increase the other increase)
by looking at combined gas law and adding avogadro’s law, we learn that any gas can be described by its_, _, _, and _
pressure, volume, temp, number of moles
P(pressure)V(volume) =
n(number of moles) R(0.08206) T(temp in K)
what is the volume of a 1.00 mole of a gas at STP?
22.4L
- if we are not at STP we have to use the ideal gas law equation
ideal gas law equation
PV = nRT
when at STP, 1atm=_K, and 1mol gas = _ L
273, 22.4L
when not at STP, use _ to find the number of moles
stoichemetry
dalton gave us _ theory and law of _ _
atomic theory
law of partial pressure
law of partial pressure
pressure a gas exerts is the same if it is in a mixture of gases or by itself
partial pressure
the pressure of an individual gas when its in a mixture
vapor pressure
pressure of a gas
ideal gas law for law of partial pressure
ntotal = n1 + n2 + n3
n = PV/RT
Ptotal = p1 + p2 + p3
PtVt/RTt = P1V1/RT1 + 2 + 3 . . .
mole fraction
mole of gas 1 / total moles of mixture
x1 = n1 / ntotal
partial pressure formula
mole fraction x Ptotal
