Atomic Fundamentals

Question 1

atom

Answer 1

a unit of matter

Question 2

proton
neutron
electron

Answer 2

subatomic particles with positive, neutral, and negative charge

Question 3

atomic #

Answer 3

the # of protons; defines an element

Question 4

atomic mass

Answer 4

the # of nucleons (protons+neutrons), aka the mass #; measured in amu

Question 5

ion

Answer 5

a charged atom; opposite is a “neutral atom”

Question 6

isotopes

Answer 6

atoms of the same element but different mass #s (still stable though)

Question 7

average atomic mass

Answer 7

(mass of isotope A x percent abundance of isotope A) + (mass of isotope B x percent abundance of isotope B)
1. multiply each mass & % to decimal forms
2. add products and apply rules (SF dp rules of the GIVEN MASS)

Question 8

percent abundance

Answer 8

a percentage showing how common an isotope is in the given sample

Question 9

Dalton’s Atomic Theory

Answer 9

1804
1. all matter is made of tiny particles, atoms, which can’t be subdivided, created, or destroyed (!)
2. atoms from the same element are identical in composition and properties, while dif. atoms have dif. II (!)
3. atoms of different elements combine in simple, whole # rations to form compounds
4. in chemical reactions, atoms combine, separate, or rearrange but are never created, destroyed, or changed

Question 10

J.J. Thomson’s Theory of Electrons

Answer 10

1897:
Thomson discovered electrons by using a cathode ray tube, showing particles of matter with negative charge, subatomic, and the same across all elements.

Question 11

The Thomson Model

Answer 11

The plum and pudding model

Question 12

Rutherford’s Gold Foil Experiment

Answer 12

1908:
The discovery of the nucleus when [—] bounced back, later discovered protons

Question 13

Rutherford’s Criticisms

Answer 13

1. mass # doesn’t equal protons and electrons (James Chadwick discovers neutrons later)
2. how do protons stick together? “strong nuclear force”

Question 14

Speed

Answer 14

always 3.00 x 10^8 m/s

Question 15

wavelength

Answer 15

“lambda”: measured in nm (10^-9m)

Question 16

energy

Answer 16

“E”: measured in Joules; low wavelength = high E, high wavelength = low E

Question 17

emission spectrum

Answer 17

each element’s unique variety of wavelengths

Question 18

The Bohr Model

Answer 18

1. electrons absorb light (energy)
2. electrons jump to excited state (up to outer shells)
3. electron relaxes back to ground state
4. energy is released as light

Question 19

relationship between energy & wavelengths

Answer 19

small E = less photon emission = long wavelengths
big E = more photon emission = short wavelengths

Question 20

why do different elements emit different wavelengths?

Answer 20

different energies jump shells at different distances

Question 21

wave-particle duality

Answer 21

treating electrons as resulting particles of inconsistent behavior, as “loops” vibrating with whole # cycles

Question 22

subshells

Answer 22

aka sublevels, next level inside shells; s, p, d, and f are different electrons wave shapes

Question 23

orbitals

Answer 23

next level in subshells; are pockets that hold 2 e-

Question 24

electron configurations

Answer 24

describes how electrons are arranged around the nucleus of any given atom

Question 25

orbital filling rules

Answer 25

1. Aufbau principle: electrons fill lower energy orbitals before occupying higher energy orbitals
2. Pauli Exclusion Principle: at most 2 electrons per orbital, each w dif. spin
3. Hund’s Rule: each orbital in a sublevel takes 1 electron before 2 pair up

Question 26

know how-to:
- aufbau diagram
- extended/full e- config.
- noble gas shorthand

Answer 26

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