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fall semester 2024-25 LSSU > chem exam #1 - sept 20 > Flashcards

chem exam #1 - sept 20 Flashcards

*also study week one notes

1
Q

subatomic particles

A

the neutrons, protons and electrons in an atom

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2
Q

jj thompson and the cathde ray tube (1897)

A
  • cathode ray tube (glass tube with most of air removed) is connected to power supply, this generates cathode rays (streams of e-)
  • cathode ray passed into region beyond power supply
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3
Q

thompson found that by applying electric or magnetic fields…

A

he could bend the cathode rays
- this allowed him to calculate mass-to-charge ratio of e- (plum pudding model

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4
Q

robert millikans oil drop experiment

A
  • generated very tiny oil drops that fell toward a neg-charged plate
  • x-ray beam generates e- that stick to the oil drops
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5
Q

R.M. -1) by changing the charge on the plate he could…
- 2) by using mass-charge ratio from thompson…

A

1) - change the rate at which the oil drops fell
- determined charge of an e- (-1.602 x10^-19 coulomb)
2) calculated mass of an e- (9.109 x10 ^-31)

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6
Q

1896, Henri Becquerel discovered…

A

radiation being emitted by the mineral pitchblende

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7
Q

becquerel, curie’s, and rutherford discovered it was…

A

several types of radiation

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8
Q

rutherford found beta particles

A

(B) - equivalent in mass and charge to high energy electron

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9
Q

alpha particles

A

(fish) - equivalent in charge to 4He nucleus (2 protons, 2 neutrons)

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10
Q

alpha and beta particles get deflected in…

A

opposite directions by electric fields

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11
Q

rutherford gold foil experiment 1909

A
  • had two graduate students test the plum pudding model
  • bombard thin gold sheet w alpha particles
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12
Q

if the plum pudding model was correct…

A

the alpha particles should pass right through with some minor deflection

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13
Q

results of gold foil

A
  • about 1 in 8000 particles deflected an average of 90 degrees, some bounced straight back (some fraction of alpha particles encountered a region of high pos. charge and mass)
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14
Q

1920, consensus that all nuclei contain …

A

protons

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15
Q

1932, neutrons were characterized in the…

A

nucleus

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16
Q

each proton and neutron has a mass of…

A

1 unified atomic mass unit, also called daltons (Da)

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17
Q

isotopes

A

atoms of the same element that have the same # of protons, but a diff # of neutrons on nuclei

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18
Q

nuclide

A

any atom of any element that has a particular # of neutrons in its nucleus

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19
Q

a
z X

A

a is mass number (#protons + #neutrons), z is atomic number (#protons)
*normally leave out atomic number

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20
Q

protons=

A

atomic #

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21
Q

neutrons =

A

mass = p + n
mass - p = n

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22
Q

electrons=

A

charge changes # of protons

23
Q

7 horizontal rows called – and 18 columns called —

A
  • periods
  • groups/families
24
Q

elements can be broadly categorized in two ways

A

1) as main group or transition metals
2) categorizes elements as metals, nonmetals or metalloids

25
Q

all elements can form ions:

A

cations = pos. charged ions
anions = neg. charged ions

26
Q

name the groups: 1, 2, 16, 17, 18

A

1- alkali metals
2- alkaline earth metals
16- chalcogens
17- halogens
18- noble gases

27
Q

average atomic mass

A

weighted average of all isotopes of an element

28
Q

natural abundance

A

proportion of a particular isotope, relative to all the isotopes of an element

29
Q

calculating average atomic mass

A

multiple mass by abundance (/100) for each, then add all up (remember sig figs by underlining insig. digits)

30
Q

molecular mass

A

the mass of one molecule of a molecular compound **mass of whole compound
(atoms/mol x atomic mass (u/atoms) = u/mol)

31
Q

formula unit

A

the smallest electrically neutral unit of an ionic compound

32
Q

formula mass

A

mass of one formula unit of an ionic compound *mass stays same even if ion all /form unit instead of molecule (label ion as element)

33
Q

mole

A

an amount of a substance that contains a number of particles (atoms, ions, molecules) equal to avogadros constant

34
Q

avogadros constant

A

the # of atoms/ions/particles in one mole of substance (6.022 x 10^23 particles/mole) * used to cancel out atoms to find moles

35
Q

molar mass

A

g/mole, seen on the periodic table, is equal to atomic mass but expressed in g/mole

36
Q

kilo

A

10^3

37
Q

centi

A

10^-2

38
Q

nano

A

10^-9

39
Q

milli

A

10^-3

40
Q

micro

A

10^-6

41
Q

pico

A

10^-12

42
Q

to get rid of log

A

put as power of 10

43
Q

to get rid of ln

A

put as power of e

44
Q

if just log(constant) or e^(constant)

A

simplify

45
Q

sig figs

A

carry through + keep all, underline insignificant digits

46
Q

if the plum pudding model was correct, what would results of gold foil be?

A

all alpha particles would have gone through

47
Q

instead of gold foil, silver and aluminum, why might these foils of deflected fewer alpha particles?

A

smaller nuclei, odds of deflecting are lower

48
Q

proton to neutron ratio when Z increases

A

ratio also increases

49
Q

when calculation formula masses, why is the average masses of neutral atoms used not ions?

A

the mass of electrons is negligible

50
Q

finding masses of formula units

A

just find atomic mass of the whole thing

51
Q

do equal masses of two isotopes of an element contain the same number of atoms?

A

No.
g x mol/ –g (isotope #) x atoms/mol (avogadros constant)
- heavier isotopes have fewer atoms

52
Q

find the number of moles given atoms or molecules

A

divide by avogadros constant

53
Q

find moles given g

A

use molar mass

fall semester 2024-25 LSSU (10 decks)

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