full chem review - khan academy lessons

Question 1

what is an isotope

Answer 1

different versions of an element

has same # of protons, but diff # of neutrons

Question 2

what is the atomic number

Answer 2

the number on top of the element in the periodic table

signifies the number of protons

Question 3

what is mass spectrometry used for

Answer 3

to find the relative abundance of each isotope

(tells you how much of an isotope is present in nature)

Question 4

relative abundance

Answer 4

% of atoms w/ a specified atomic mass found in naturally occurring sample of an element

Question 5

avg. atomic mass + how to find

Answer 5

weighted average calculated by multiplying the relative abundances of the element’s isotopes by their atomic masses and then summing the products

Question 6

how to tell which compound has the greatest % mass carbon if all of them have the same moles of carbon?

Answer 6

the compound with the lowest GFM will have the greatest mass %

Question 7

Coloumb’s Law

Answer 7

magnitude of force between 2 charged particles is proportional to the charge on the 1st particle times the charge on the 2nd particle divided by the distance b/w those 2 particles squared

F = (q1q2) / (r)^2

Question 8

Z effective equation

Answer 8

atomic number - # of core electrons (the ones in 1s)

Z - S

Question 9

atomic radius trend

Answer 9

increases as you go down and towards the left

Question 10

first ionization energy

Answer 10

minimum energy required to remove first valence electron

• ionization energy is higher when coloumb forces are higher (greater Z* and lower radius)

Question 11

electron shielding

Answer 11

blocking of valence shell electron attraction by the nucleus, due to presence of inner shell electrons

Question 12

electron affinity

Answer 12

how much energy is released if we ADD an electron to a neutral version of a given element

(highest electron affinity near F and Cl)

the elements with the higher electron affinity are the ones that really want electrons!

also depends on energy sublevel

Question 13

nuclear charge

Answer 13

of protons in the nucleus

Question 14

why is second ionization energy greater than first

Answer 14

electron shielding

the second electron is harder to remove because less electron shielding so the valence electron can actually feel more pull from the nuclear charge

Question 15

electronegativity

Answer 15

atom shares pair of electrons w/ another atom, how likely is it to attract the pair to itself vs. pair to be attracted to the other one

Question 16

Ionic radius (depends on 3 things)

Answer 16

depends on: nuclear charge, # of electrons, and electron shell of its outermost electrons

if electron configurations are the same (isoelectronic), use nuclear charge

larger nuclear charge = smaller radii