Chemistry: Chapter 4 and 5 [DONE]

Question 1

What did Democritus reason about atoms?

Answer 1

he said that they were indivisible and indestructible; he turned Dalton’s ideas into a scientific theory by using scientific methods

Question 2

What do scientists use to observe atoms?

Answer 2

Scanning electron microscopes

Question 3

define atom (2)

Answer 3

• the SMALLEST particle of an element

- it retains its identity in a chemical reaction

Question 4

define Dalton’s Atomic Theory: (4)

Answer 4

1. All elements are composed of atoms
2. atoms of the same element are identical, but atoms from different elements are ALL different
3. atoms of different elements can mix together to form a compound
4. chemical reactions occur when atoms are separated from each other, joined, or rearranged in a different combination. *Atoms of one element can NEVER be changed into another element from a chemical reaction.

Question 5

What are the three types of subatomic particles?

What are their charges?

What are their masses?

Answer 5

• protons, neutrons, and electrons
• positive, neutral, and negative
• 1, 1, 1/1840

Question 6

What is the actual structure of a nuclear atom?

Answer 6

• Protons and neutrons are contained inside of the nucleus.

- Electrons reside in orbitals AROUND the nucleus

Question 7

define electron?

who discovered electrons?

Answer 7

• a negatively charged subatomic particle

- J.J. Thomson

Question 8

define cathode ray:

what was the final results in the experiment conducted by J.J. Thomson

Answer 8

• a glowing beam that Thomson used in an experiment

- found that a positively charged plate ATTRACTS the cathode ray and a negatively charged plate REPELS the cathode ray.

Question 9

Define proton:

who discovered protons?

Answer 9

• a positively charged subatomic particle

- Ernest Rutherford

Question 10

define neutron:

who discovered neutrons?

Answer 10

• a neutrally charged subatomic particle

- James Chadwick

Question 11

define nucleus:

Answer 11

• the center / core of an atom

Question 12

What was later discovered about atoms?

Answer 12

• that they actually ARE divisible, which means that they can be divided without losing their properties.

Question 13

what makes one element different from another?

Answer 13

the number of protons

*every element has a different number

Question 14

How do isotopes of an element differ?

Answer 14

because isotopes of an element have a different number of neutrons and different mass numbers

Question 15

How to calculate the atomic mass of an element?

Answer 15

(mass of isotope x natural abundance in decimal form = x ) + (mass of isotope x natural abundance in decimal form = x), etc…

• do that for however many isotopes it gives you and then add the products

Question 16

define atomic number

Answer 16

the number of protons in the nucleus of an atom of the element

Question 17

define mass number

Answer 17

total number of protons and neutrons in an atom

Question 17

What did Niels Bohr propose in his model of the atom?

Answer 17

He proposed that an electron is found only in orbits around the nucleus.

Question 18

what does the quantum mechanical model determine about the electrons in an atom?

Answer 18

the allowed energies an electron can have and how likely It is to find the electron in various locations?

Question 18

How to find the number of neutrons in an atom?

Answer 18

of neutrons = mass # - atomic #

• Mass # = rounded to a whole number

Question 19

define isotope

Answer 19

atoms of the same element that have the same atomic number, but different atomic masses due to a different number of neutrons

Question 20

How to find protons?

Answer 20

it’s the atomic number of an element

Question 20

define quantum mechanical model

Answer 20

the behavior of electrons in atoms

Question 21

how to find electrons

Answer 21

*same as the number of protons

Question 21

define atomic orbital (2)

Answer 21

a mathematical expression describing the probability of finding an electron at various locations represented by the denser area surrounding a nucleus (higher probability of finding an electron)

Question 22

define atomic mass

Answer 22

the weighted average of the masses of the isotopes of an element

Question 23

define atomic mass unit (amu)

Answer 23

a unit of mass equal to one-twelfth the mass of a carbon-12 atom

Question 24

What were the ideas concerning the structure of an atom involving Thomson and Rutherford?

Answer 24

Thomson - believed that electrons were evenly distributed throughout the atom filled uniformly with positively charged material. Rutherford - tested Thomson's model of atomic structure through the gold-foil experiment --> led to his idea that the atom was mostly empty space

Question 24

define energy level

Answer 24

the specific energies an electron in an atom or other system can have

Question 25

what causes atomic emission spectra? (2)

Answer 25

- absorbing energy (electrons move to higher energy levels) | - emitting light (loses electrons when they return to lower energy levels)

Question 26

How does quantum mechanics differ from classical mechanics?

Answer 26

- classical mechanics describe the motions of bodies much larger than atoms - quantum mechanics describes the motions of subatomic particles and atoms as waves

Question 27

define quantum

Answer 27

the amount of energy needed to move an electron from one energy level to another

Question 28

# define wavelength what is the unit for wavelength?

Answer 28

- the distance between adjacent crests of a wave | - measured in meters

Question 29

# define frequency what is the unit of frequency?

Answer 29

- the # of wave cycles that pass a given point per unit of time - Hertz (Hz) or s^-1

Question 30

define electromagnetic radiation

Answer 30

energy waves that travel in a vacuum at a speed of 2.998 x 10^8 m/s (c= wavelength x frequency)

Question 31

what are the 3 rules for writing the electron configuration of elements? * what does it do?

Answer 31

1. the Aufbau Principal 2. the Pauli Exclusion Principle 3. Hund's Rule * it tells you how to find the electron configurations of atoms

Question 32

how did Einstein explain the photoelectric effect?

Answer 32

he proposed that light could be described as quanta of energy that behave as if they were particles

Question 33

define atomic emission spectrum

Answer 33

the pattern formed when light passes through a prism

Question 34

define Planck's Constant

Answer 34

(h) a number used to calculate the radiant energy (E) absorbed or emitted by a body based on the frequency of radiation E = (6.626 x 10^-34) x frequency

Question 35

define electron configuration

Answer 35

the arrangement of electrons of an atom in its ground state into various orbitals around the nuclei of atoms

Question 36

define spin

Answer 36

a quantum mechanical property of electrons that may be thought of as clockwise or counterclockwise

Question 37

define amplitude

Answer 37

the height of a wave's crest

Question 38

what is the order of the electromagnetic spectrum from lowest frequency to the highest frequency: what are the colors?

Answer 38

Radio Waves, Radar, Microwaves, Infrared, Ultraviolet, X-Rays, Gamma Rays - R.O.Y.G.B.I.V.

Question 39

order of the electromagnetic spectrum from lowest wavelength to the longest wavelength:

Answer 39

Gamma Rays, X-Rays, Ultraviolet, Infrared, Microwaves, Radar, Radio Waves

Question 40

define photoelectric effect:

Answer 40

the ejection of electrons by certain metals when they absorb light with a frequency above a threshold frequency

Question 41

define photon

Answer 41

a quantum (amount of energy needed to move an electron from one level to another) of light - a discrete bundle of electromagnetic energy that interacts with matter similarly to particles

Question 42

define ground state

Answer 42

the lowest possible energy of an atom described by quantum mechanics

Question 43

define Heisenberg uncertainty principle

Answer 43

it is impossible to know exactly both the velocity and the position of a particle at the same time