Chem 4a quiz

Question 1

Democritus

Answer 1

Matter is made of separate distinct particles
Could not be divided infinitely without losing its properties
Atomos

Question 2

Dalton’s Atomic Model

Answer 2

First experimental model
Theories: Combinations of atoms from different elements form compounds
Atoms of different elements have different masses
He assigned relative masses to atoms of various elements
Not entirely accurate

Question 3

Law of definite composition

Answer 3

Every compound is formed of elements combined in specific ratios by mass that are unique for that compound

Question 4

1800 Alessandro Volta

Answer 4

Italian physicist and chemist
Discovered methane gas
Invented electrical battery

Question 5

JJ Thomson’s model

Answer 5

Experiments with cathode rays
Negative charged particles
Electrons
Electrons have very little mass
Plum pudding model

Question 6

1909 Discovery of the Nucleus

Answer 6

Rutherford’s model
The Geiger experiment

Question 7

What did we learn from the Geiger Experiment

Answer 7

Nucleus= very small compared to whole atom
Nucleus has positive charge
Positive particles in nucleus= protons
Number of protons in nucleus called atom’s atomic number

Question 8

James Chadwick observed

Answer 8

Neutrally charged particles in a sample of metal
Neutrons are slightly heavier than protons
Neutron discovery

Question 9

What did we learn from the Rutherford and Geiger experiment
A) Atom’s nucleus is tiny
B) Atoms have lots of empty space
C) Protons are in nucleus and thus positive
D) All of above

Answer 9

D

Question 10

Thompson’s contribution to our understanding of the atom was
A) Electrons and their + charge
B) Electrons and their - charge
C) Protons
D) Cathode ray tubes

Answer 10

B

Question 11

Discovery of Electron Energy: Bohr

Answer 11

Questions:
Why do electrons not fall into nucleus
Are they moving
How are electrons arranged
Thought electrons needed movement and energy to keep from crashing into the nucleus
Developed model of the atom

Question 12

Do electrons go through the nucleus

Answer 12

Yes

Question 13

Electromagnetic spectrum

Answer 13

We can tell only when electrons give off energy in the form of colored light.
Most of the time when electrons give off energy, we don’t see it with our eyes (Microwaves, x-ray, UV, infared)

Question 14

How do we show the information of electrons giving off energy

Answer 14

Electrons will form a spectrum and we can read it

Question 15

Basic types of spectra aka…

Answer 15

Fingerprints of light

Question 16

Continuous spectrum

Answer 16

When white light is passed through a prism
Contains all wavelengths of visible light

Question 17

Line spectrum

Answer 17

Each line corresponds to a discrete wavelength
Hydrogen emission spectrum

Question 18

What’s the difference between emission spectrum and absorption spectrum
A) Absorption has colored lines, emission has black lines inside the rainbow of colors
B) Emission has the colored lines, absorption has black lines inside rainbow of colors

Answer 18

B

Question 19

Rainbow is example of what type of spectrum
A) Absorption
B) Emission
C) Continuous

Answer 19

C

Question 20

What is Spectroscopy

Answer 20

Studies spectra
Analyze light given off by matter
Analyze light absorbed by matter

Question 21

Spectrum

Answer 21

Shows the different wavelengths of light and energy
Fingerprint of light

Question 22

What did we learn because of spectroscopy

Answer 22

Principal energy levels
These levels are quantized
Quantized- Energy is given off in specific amounts

Question 23

Electrons can do 3 things

Answer 23

Absorb energy, then it jumps to a higher lvl
Give off energy, while they fall back to lower lvl
Ground state- lowest energy lvl in system

Question 24

T/F Every element has its own unique spectrum

Answer 24

True

Question 25

Bohr’s atomic model matched the spectrum of
A) Hydrogen and every other element
B) Hydrogen and Gold only
C) Hydrogen by itself

Answer 25

C

Question 26

When do we see electron activity

Answer 26

When they give off energy

Question 27

De Broglie’s hypothesis

Answer 27

Light has properties of both waves and particles
Photons- packets of energy
Electrons have a dual nature: Wave-particle duality

Question 28

Heisenberg uncertainty principle

Answer 28

Impossible to know both the energy and location of an electron in an atom
Orbitals/sublvls started here
Probable positions of electrons

Question 29

Electron cloud model

Answer 29

Cloud of negative charge surrounding nucleus that shows areas where electron is likely to be found
90% probability