Gen Chem 1 Flashcards
What is the atomic number (Z)
the number of protons an atom has
What is the mass number (A)
the combined number of protons and neutrons
When the convention showing the atom, it’s atomic number and mass number how is it arranged
the mass number on top of the atomic number. both next to the atom name
What are valence electrons
electrons farthest away from the nucelus
what happens to valence electrons as they get farther away from the nucleus
the farther away they are the less they are attracted to the nucleus, and the more they can interact with other atoms.
What is an ion
a positive or negative atom due to the loss or gain of electrons
how many, n’s, p’s, and e-‘s in a Nickel-58 atom
Ni = 28 protons
58-28 = 30 neutrons
since it is neutral it has 28 electrons too
How many n’s p’s, and e-‘s does a +2 Nickel-60 atom have
Ni = 28 protons
60-28 = 32 Neutrons
Since it is plus 2 it has lost 2 electrons = 26 e-‘s
How much is one amu in grams
1.66 x 10^-24
How many amu does carbon have
12
what is the atomic weight
the weight in grams of one mole of a given element (g/mol)
What is avogadro’s number
the number of particles in a mole
6.022 x 10^23
What are isotopes
when atoms (having the same number of protons) have different numbers of neutrons
how does isotopicity affect reactivity
it doesn’t change a lot because they still have the same number of protons and e-‘s
How is the atomic weight of the elements on the periodic table found
you take the mass number of each of the isotopes multiplied by the frequency of that isotope, and add all of those together
Q has
isotope A 60% at 40 amu
isotope B 25% at 44 amu
isotope C 15% at 41 amu
40 x .6 = 24
44 x .25 = 11
41 x .15 = 6.15
24 + 11 + 6.15 = 41.15 g/mol
What is plancks constant
6.626 x 10^-34 J*s
what is the equation for the energy of a quantum
E = hf h = plancks constant f = frequency
What is the equation for the angular momentum of an electron
angular momentum = nh/2pie
n = quantum number
h = plancks constant
What is bohrs model of the Hydrogen atom
a single proton with an electron circling it
Since angular momentum of an electron has thee different constants in the equation, what determines angular momentum of an electron
the quantum number
What is the equation for the energy of an electron
E = -Rh/n^2 Rh = 2.18 X 10 ^-18 j/electron
What is Rh
the rydberg constant = 2.18 x 10^-18 j/electron
What is the only factor that affects the energy of an electron
the quantum number
What will the energy of an electron be in any of it’s quantized states
negatve
The energy of an electron is related to
it’s orbital radius the larger the radius the more energy it has. the smaller the radius the less energy it has
what is the smallest orbit an electron can have
n = 1
What is the ground state level for an electron
when the electron is at it’s lowest energy state
How is atomic emission specrta gathered
you take an atom in its ground state, then heat it up or add energy to it and the electron is excited, or moved to a higher energy state. It will quickly move back to it’s ground state but in doing so it will release energy in the form of photons.
What is the equation for the energy of the photons released when doing atomic emission spectra
E = hc/Lambda H = plancks constant c = speed of light Lambda = wavelength
What is the speed of light
3 x 10^8 m/s
How are atomic emission spectra used to identify an element
each electron in a element when returning to ground state releases a specific wavelength of light, each element has its own specific electrons so each element has it’s own unique atomic emission spectrum
Can the atomic emission spectrum of stars be done
ye[p
What is the balmer series of hydrogen emission lines
transitions from n > 2 to n = 2
how many wavelengths are in a balmer series of hydrogen emission lines
4 in the visible region
what is the lyman series of hydrogen emission lines
transitions fron n > 1 to n = 1
what causes an electron to jump up to a higher energy state
it absorbs energy
what is an absorption spectrum
it is the spectrum showing which wavelengths of energy are absorbed by a specific element
When can absorption spectrum be used
in the identification of elements present in a gas phase sample
Why does Bohr’s model not work for atoms with more than one e-
because it doesn’t take the repulsion between each electron into account
What is the main difference between Bohr’s model and modern quantum mechanics
that electrons don’t go around the nucleus in a circle, but they move around in orbitals
what does an electron orbital show
it represents the probability of finding an electron in a given region
what is the Heisenberg uncertainty principle
states that it is impossible to determine with perfect accuracy the momentum and position of an electron simultaneously
What are the four quantum numbers
n, ℓ, mℓ, ms
What is the pauli exclusion principle
no two electrons in a given atom can posses the same set of four quantum numbers.
What does the position and energy of an electron described by its quantum numbers give you
its energy state
What is the quantum number n and what does it indicate
the principal quantum number
it indicates the distance of the electrons from the nucleus
What is the quantum number ℓ and what does it indicate
the azimuthal quantum number (angular momentum quantum number)
it refers to the subshells of the valence electrons
what do the ℓ quantum numbers 0 1 2 3 indicate
0 means that the electrons are in the S subshell
1 means the p subshell
2 = d subshell
3 = f subshell
With using ℓ, how many electrons can fill particular subshells
4f + 2
the greater the number of ℓ, the
greater the energy of the subshell
what is the quantum number mℓ, and what does it indicate
it is the magnetic quantum number
it indicates which orbital
how many mℓ values can there be in terms of ℓ
2ℓ + 1
What is the ms quantum number and what does it indicate
it is the spin quantum number
and it is just the last way to identify electrons (both electrons in one orbital must have opposite spins
What are electrons with parallel spins
electrons in different orbitals with the same Ms values
What are paired electrons
electrons in the same orbital with opposite spins
In the electron configuration what does the
1st number
letter
2nd number indicate
- the principal energy level
- the subshell
- the number of electrons in that subshell
how do you know which subshells will fill first
those with a lower n + ℓ value, if they are tied, then you go with the one with the lower n value
In what order are subshells filled
1s 2s 2p 3s 3p 4s 3d 4p 5s 4d 5p 6s
What is hund’s rule
all orbitals of the same energy level fill halfway before any will completely fill
What are some exceptions to the orbital filling rules
Chromium
- expected = 1s2, 2s2, 2p6, 3s2, 3p6, 4s2, 3d4
- actual = 1s2, 2s2, 2p6, 3s2, 3p6, 4s1, 3d5
This is so that the 3d orbitals can be half filled
Copper
- does the same thing except 5 electrons later, one e- is promoted to the 3d orbital from the 4s obital to give it 10 e-‘s
what are paramagnetic materials
materials with unpaired electrons, that are weakly attracted to a magnetic field
What are diamagnetic materials
materials with no unpaired electrons that are slightly repelled by a magnetic field
What are valence electrons
all of the electrons in it’s outer energy shell
What is the periodic law
that the chemical properties of the elements are largely dependent on their atomic number
What are the periods of the p table
rows
what are the groups on the p table
columns
what does the roman numerals on the periodic table groups indicate
the number of valence electrons
What does the A or B indicate after the roman numeral
A = representative elements (either s or p as outermost orbitals) B = nonrepresentative elements ( have d as their outermost orbitals)
What are the two kinds of non-representative elements
transition elements
lanthanide and actinide serie
what are transition elements
those with partially filled d orbitals
what are lanthanide and actinide elements
those with partially filled f orbitals
what do all elements strive for
8 valence electrons
how does atom size radii across the p table
as you go from left to right they get smaller
as you go from bottom to top they get smaller
how do they find atomic radii
it is one half of the distance between to atoms of that element that are just touching each other
why does atomic radii get smaller towards the top right of the p table
from left to right because the more protons and electrons you have the more that they are pulled together
from bottom to top because filled orbitals block the attraction for the valence electrons and the nucleus.
what is the ionization energy
the amount of energy required to remove an electron from an atom
how does ionization energy change on the p table
the same way that atomic radii does. it is the largest in the top right because the electrons are the most tightly held together
what is first and second ionization energy and how do they compar
first ionization energy describes the energy required to remove the first electron, second “ “ second electron
second ionization energy is always greater than the first ionization energy
What is electron affinity
the energy change that occurs when an electron is added to a gaseous atom, (it represents the ease with which an atom can accept an electron)
how does atomic size affect electronegativity
the smaller the atom, the more it will pull on the electron
how does electronegativity change across the p table
it increases towards the top left
what is the effective nuclear charge (Zeff)
the attractive pull of the nucleus (increases from left to right)(more protons)
What is electronegativity
the measure of attraction an atom has for electrons in a chemical bond.
what is special about cesium
-largest
- most metallic
least electronegative of all naturally occurring elements
- smallest ionization energy
- least exothermic electron affinity
What is another way to think about electronegativity
nuclear positivity
the stronger the nuclear pull the more electronegative it will be
What is the most electronegative atom
fluorine
What are the three types of elements
metals
non-metals
metalloids (semimetals)
where are metals, non-metals, and mettaloids located on the p tabel
metals left of the ziggy line
non-metals on the right of the ziggy line
mettaloids form the ziggy line
What are the characteristics of metals
- shiny solids at room temperature (except mercury)
- high melting points
- high densitties
- malleable
- ductile
- low ionization energies
- low electronegativity
What is malleability
the ability of a metal to be hammered into shapes
What is ductility
the ability to be drawn into wire
What gives rise to the characteristic properties of metals
the few electrons in the valence shells can easily be removed
What makes metals good conductors of heat and electricity
that their electrons can easily be moved.
What are some of the characteristics of non-metals
- brittle in solid state
- little or no luster
- high ionization energies and electronegativities
- gain electrons easily
What are some of the characteristics of metalloids
- posses characteristics of both metals and non-metals
What elements are metalloids
Boron Silicon Germanium Arsenic Antimony Tellurium (polonium)
What are alkali metals
elements in group IA
What are the characteristics of alkali metals
- one loosely bound e-
- highly reactive due to low ionization energies
- react highly with halogens
What are alkaline earths
elements in group IIA
What are some of the characteristics of alkaline earths
- large atomic radii
- fairly loosely bound electrons 2
- low electronegativity, ionization energies, and electron affinities
What are halogens
elements in group VIIA
What are the characteristics of halogens
- 7 valence electrons
- high electronegativities
What are the physical states of halogens at room temperature
F and Cl are gasses
Br is a liquid
I is a solid
What are the noble gases
the elements of group VIIIA
what are the charateristics of the noble gasses
- quite unreactive
- high ionization energies
- low boiling points
- all gasses at room temp
What are the transition elements
elements in group IB to VIIIB
What are the charateristics of transition elements
- very hard
- high melting points
- malleable
- highly electrically conductive
- low ionization energies
What are the positively charged transition metals called
oxidation states
What causes transition metals to be malleable and conductive
they have loosely held d-orbital electrons
What is it called when transition metals in their oxidation states complex with water molecules, or nonmetals
hydration complex (with water) complexes without
What happens with complexes
they absorb a wide variety of frequencies of lights. which leads to interesting colors of liquids.
What interacts to form bonds between molecules
the valence electrons of molecules
what is the difference between intramolecular forces and intermolecular forces
intra = the forces that actually hold the two atoms together inter = other forces within the molecule that are between atoms that aren't bonded
What is the octet rule
that atoms bond to other atoms until they have 8 electrons in their outermost electron shell
what are exceptions to the octet rule
Hydrogen (2 or 4) Lithium and beryllium (2 or 4) Boron (6) elements beyond the second row phosphorus and sulfur (8+)
What is ionic bonding
when electrons from an atom with a small ionization energy are transferred to an atom with a high electron affinity.
what kinds of forces hold ionic bonds together
electrostatic
what is covalent bonding
When an electron pair is shared between two atoms.
What is it called when the bonds are partially covalent and partially ionic
polar covalent bonds
in which kind of bond are electrons completely donated, what kind are they just shared
donated in ionic
shared in covalent
how large does the difference in electronegativity need to be for it to be a strong enough ionic bond to create cations and anions
at least 1.7 difference or larger
what are the characteristics of ionic compounds
- high boiling and melting points
- conduct electricity in the liquid and aqueous states (not in solid states)
- form crystal lattices that increase attractive forces and decrease repulsive forces
What kind of bond is formed when elements of similar electronegativities bind
covalent bond
which is requires more energy. the creation of two ions, or the energy released when an ionic bond is broken
the energy required to create ionic bonds
what are the characteristics of covalent compounds
- weak intermolecular forces
- low melting solids
- do not conduct electricity in liquid or aqueous states
what is bond order
it tells you how many electron pairs are shared in a bond
single bond = bond order of 1
double bond = bond order of 2
…
What are the two features of a covalent bond
bond length
bond order
how are bond order and bond length related
higher bond orders = shorter bond lengths
What is bond energy
the amount of energy required to seperate two bonded items
how is bond order and bond energy related
the higher the order the higher the bond energy
what is a formal charge
when more or less electrons are attributed to an atom in a molecule than would be alone
What are the steps of drawing lewis structures
- Draw the skeletal structure of the molecule
- count all of the valence e-‘s (sum = total number of electrons)
- draw single bonds
- complete all of the octets (outside atoms first)
- put extra electrons on the central atom
- double or triple bonds if needed
How do you calculate the formal charge of an atom
- take the number of valence electrons it normally has
- subtract half of all the bonding electrons
- subtract all of the non-bonding electrons
What is a resonance structure
when two or more non-identical lewis structures can be drawn
how do we know which resonance structure is the actual molecule
it’s not one or the other but a hybrid of both, it spends more time, or is more like the more stable of the two resonance structures
What kind of arrow represents resonance structures
one double headed arrow
Are lewis structures with formal charges preferred over lewis structures without formal charges
no structures without formal charges are more preferred
What are some exceptions to the octet rule
atoms found in or below the third period can have more than 8 valence electrons because the D orbital can hold some
What are polar covalent bonds
bonds formed between atoms with small electronegativity (.4-1.7)
the electron pair is held more closely to the more electronegative atom
and thus it has a partial negative charge and the other has a partial positive charge
what is a dipole moment
the product of charge magnitude and the distance between the partial charges in a polar covalent bond
What are coordinate covalent bonds
when the bonding electron pair comes from only one of the two atoms
where are coordinate covalent bonds normally found
in lewis acid-base complexes
what is a lewis acid
what is a lewis base
lewis base = electron pair donor
lewis acid = electron pair acceptor
2 regions of electron density
shape and degree
linear
180 degrees
3 regions of electron density
trigonal planar
120 degrees
4 regions of electron density
tetrahedral 109.5 degrees
5 regions of electron density
trigonal bipyrimidal
90, 120, 180 degrees
6 regions of electron density
octahedral
90, 180 degrees
What does an ℓ=0 orbital look like
it is an s-orbital
a perfect sphere
What does a ℓ=1 orbital look like
that is a p-orbital
there are three along the x,y,and z axis. they are two baloons tied together shape (dumbell)
What does a ℓ=2 orbital look like
That is a d orbital
you don’t need to know
What is a molecular orbital
when two atomic orbitals interact during a bond
What is the molecular orbital of a single bond
both of the orbitals overlap head to head and form sigma bond
What is the molecular orbital of a double bond
the orbitals are parallel and it is called a pie bond
How do you get a bonding orbital
when the two bonding atomic orbitals are the same sign, they bond
how do you get a non-bonding orbital
when the two bonding orbitals are opposite signs, they don’t bond
What are intermolecular forces
forces between molecule
What are the kinds of intermolecular forces
Dipole-dipole interactions
hydrogen bonding
dispersion forces
What are dipole dipole interactions
when the polar (+) end of one molecule orients itself near the polar ( - ) end of another molecule
when do dipole dipole interactions occur
in solid and liquid phases
gasses the molecules are too spread out
what can dipole-dipole interactions do for a solid or molecule
they can increase the melting and boiling points compared to non-polar substances of the same weight
What is hydrogen bonding
when a H bonded to an electronegative atom (F,O,N) and it’s partial positive charge interacts with the partial negative charge on other molecules
what does hydrogen bonding do to the melting point and boiling points of molecules
raises them significantly
what kinds of molecules have greater dispersion forces
large atomed molecules
what determines if molecules are miscible or immiscible
the intermolecular forces
what is a compound
a pure substance that is composed of two or more elements in a fixed portion
What is the ionic substitute for molecular weight
formula weight
What is the Gram Equivalent weight
the molar mass (how many grams per mole a substance is)
divided by the number of (hydrogens) that the substance can supply.
how do you find equivalents
weight of the compound / Gram equivalent weight