General Chemistry

Question 1

Mass Number (A)

Answer 1

sum of the protons and neutrons in the atom’s nucleus

Question 2

Atoms that share an atomic number but have different mass numbers.

Answer 2

Isotopes

different number of neutrons

Question 3

Atomic Number (Z)

Answer 3

number of protons found in that element

Question 4

The electrons closer to the nucleus have [higher or lower] energy levels compared to those further out?

Answer 4

close = LOW energy
far = HIGH energy

Question 5

Atomic Mass/Mass Number vs Atomic Weight

Answer 5

Atomic Mass/Mass Number is the cold sum of the number of protons and neutrons

Atomic Weight the the WEIGHTED AVERAGE of all the different isotopes that exist of an atom

Question 6

A mole is equal to …

Answer 6

Avogadro’s Number

Na = 6.02 x 10^23

Question 7

What is the equation for the Planck relation?

Answer 7

E = hf

Question 8

An electron can be excited and jump into a higher orbit. When it returns to its ground state, it releases a discrete amount of energy in the form of a photon. The equation to describe the electromagnetic energy of these photons is …

Answer 8

E = hc / gamma

h = Planck’s constant
c = speed of light ina vacuum
gamma = wavelength of the radiation

Question 9

Pauli Exclusion Principle

Answer 9

no two electrons in a given atom can possess the same set of four quantum numbers

Question 10

Principle Quantum Number

Answer 10

denoted by the letter n

the energy level and radius of the electron shell

Question 11

Azimuthal Quantum Number

Answer 11

angular momentum designated by the letter l

shape and number of subshells within a given principle energy level (n // shell)

l = 0 to (n-1)

l = 0 is the s shell
l = 1 is the p shell
l = 2 is the d shell
l = 3 is the f shell

Question 12

Maximum number of electrons within a subshell related to the Azimuthal Quantum Number

Answer 12

max number of electrons = 4l + 2

Question 13

Magnetic Quantum Number

Answer 13

designated my m_l

specifies the particular orbital within a subshell where an electron is likely to be found

each orbital can hold a max of TWO electrons

m_l ranges from -l to +l, including 0

Question 14

Spin Quantum Number

Answer 14

denoted by m_s

opposite spin (-0.5 and +0.5) when in the same orbital

Question 15

Aufbau Principle

Answer 15

electrons fill from lower- to higher-energy subshells

each subshell will fill completely before electrons move to the next one

Question 16

Hund’s Rule

Answer 16

within a given subshell, orbitals are filled such that there a maximum number of half-filled orbitals with parallel spin

Question 17

Why would Chromium’s electron configuration be [Ar] 4s1 3d5 INSTEAD of [Ar] 4s2 3d4

Answer 17

half-filled and fully filled orbitals have LOWER ENERGIES (higher stability)

Hund’s Rule

Question 18

Paramagnetic

Answer 18

material composed of atoms with UNPAIRED electrons

aligns to the magnetic field and is slightly attracted

parallel spins

Question 19

Diamagnetic

Answer 19

materials consisting of atoms with PAIRED electrons

slightly repelled by a magnetic field

Question 20

What is the maximum number of the electrons allowed in a single atomic energy level in terms of the principle quantum number n?

Answer 20

2n^2

Question 21

Which equation describes the maximum number of electrons that can fill an orbital in terms of the Azimuthal quantum number l?

Answer 21

4l + 2

Question 22

What is the MCAT’s favorite equation?

Answer 22

E = hf = h * c / lambda (wavelength)

Question 23

Sublimation

Answer 23

phase change during which a SOLID turns into a GAS

Question 24

Deposition

Answer 24

phase change during which a GAS turns into a SOLID

Question 25

What influences the physical properties of a solid?

Answer 25

The LATTICE structure

includes its density and packing (influences density and melting point)

Question 26

What does the roman numeral in the Group name on the periodic table represent?

i.e Group VA

Answer 26

the number of valence electrons elements in that group have in their neutral state

Question 27

Effective Nuclear Charge (Zeff)

what is the general trend on the periodic table?

Answer 27

electrostatic attraction between the valence shell electrons and the nucleus

measure of he net positive charge experienced by the outermost electrons

same period: Zeff increases from left to right; more or less constant among elements in a given group

Question 28

What is the trend of atomic radii on the periodic table?

Answer 28

SMALLER up and to the right

right – increasing Zeff of adding protons holds the valence electrons tighter/closer
up – decreasing the principle quantum number n results in shells that are closer to the nucleus

Question 29

Ionization Energy (IE)

periodic trend?

Answer 29

energy required to remove an electron from a gaseous species

NOTE: removing electron always requires the input of energy, which makes it an ENDOTHERMIC process

the greater the atoms Zeff, the harder it is to strip the electron; IE increases then from left to right and bottom to top

Question 30

Which atoms have the highest ionization energies? Which have the highest second ionization energies?

Answer 30

Noble Gases have the highest ionization energies

Group IA molecules have disproportionately high second ionization energies because losing one electron makes them very stable!

Question 31

Electron Affinity

Answer 31

refers to the energy dissipated by a gaseous species when it gains an electron

EXOTHERMIC process that expels heat

HALOGENS are greedy for electrons

functionally, this is the opposite concept as ionization energy

Question 32

What is the deltaH of an atom gaining an electron?

Answer 32

deltaH < 0 negative

EXOTHERMIC; lets off energy/heat

the HIGHER/STRONGER the Zeff, then the more energy will be released

Question 33

Electronegativity

Answer 33

measure of the attractive force that an atom will exert on an electron in a chemical bond

related to ionization energy

Question 34

Alkali Metals

Answer 34

Group I metals

usually exist as univalent cations that form bonds with nonmetals

Question 35

Alkaline Earth Metals

Answer 35

Group II

usually in the form of a divalent cation

“active” metal

Question 36

Double replacement reaction?

Answer 36

Two compounds turn into TWO NEW compounds (ion swap).