chapter 3 test

Question 1

What happened in the cathode ray experiment?

Answer 1

Investigators noticed when current passed through the tube, the surface of the tube directly opposite the cathode glowed. They discovered that cathode rays were deflected by a magnetic field in the same manner as a wire carrying electric current, which was known to have a negative charge. The rays were deflected away from a negatively charged object. Cathode rays were negatively charged.

Question 2

Who supported the Cathode ray experiment?

Answer 2

JJ Thompson, he was able to measure the ratio of the charge of cathode ray particles to their mass. Discovered the electrons.

Question 3

Who measured the charge of the electrons?

Answer 3

American physicist Robert A. Milikan.

Question 4

What model did Thompson propose?

Answer 4

The plum pudding model (After English dessert). It proposed that the electrons were spread evenly throughout the positive charge of the rest of the atom. It looked like a chocolate chip cookie.

Question 5

Who provided more detail of the atom’s structure?

Answer 5

Ernest Rutherford.

Question 6

What experiment did Rutherford and his friends do?

Answer 6

The Gold Foil Experiment.

Question 7

What did the Gold Foil Experiment entail?

Answer 7

They bombarded the gold thin foil with alpha particles, positively charged. The particles slightly passed through except 1 in 8000 were deflected.

Question 8

What did Rutherford reason?

Answer 8

The deflected particles must have experienced some powerful force w/in the atom. The force must be caused by a very densely packed bundle of matter w/a positive electric charge (nucleus)

Question 9

Who did the Bohr Model?

Answer 9

Niels Bohr

Question 10

Why may two protons be attracted to each other?

Answer 10

When there are two protons are extremely close to each other, there is a strong attraction between them. (nuclear forces).

Question 11

What are the radii of atoms expressed in?

Answer 11

Picometers

Question 12

What is the atomic number?

Answer 12

The atomic number is the number of protons of each atoms of that element.

Question 13

What does the atomic number identify?

Answer 13

An element, if the number of protons were to change so were the elements.

Question 14

What are Isotopes?

Answer 14

Atoms of the same element that have different masses. The isotopes of a particular elements all have the same number of protons and electrons but different numbers of neutrons.

Question 15

What is the mass number?

Answer 15

The total number of protons and neutrons that make up the nucleus of an isotope.

Question 16

What are the two methods for specifying isotopes?

Answer 16

The mass number appears with a hyphen after the name of the element. And the superscript and subscript with the symbol at the end

Question 17

Is atomic mass a relative measure?

Answer 17

Yes

Question 18

What is average atomic mass?

Answer 18

The weighted average of the atomic masses of the naturally occurring isotopes of an element.

Question 19

True or False: Different samples of the same element can differ in their relative abundance of isotopes?

Answer 19

Yes

Question 20

What is a mole (mol)

Answer 20

The amount of a substance that contains as many particles as there are atoms in exactly 12g of carbon-12

Question 21

What is Avogrado’s number?

Answer 21

6.02214179 x 10^23: the number of particles in exactly one mole of a pure substance

Question 22

What is the molar mass of a substance?

Answer 22

The mass of one mole of a pure substance.

Question 23

Who is Democritus

Answer 23

Stated that the atomos is uncuttable; you can cut mass down until the atomos

Question 24

What is the Law of Conservation of Mass?

Answer 24

States that mass is neither created nor destroyed during ordinary chemical reactions or physical changes.

Question 25

What is the Law of Definite Proportions

Answer 25

The fact that a chemical compound contains the same elements in exactly the same proportions by mass regardless of the size of the sample or the source of the compound

Question 26

What is the law of multiple proportions?

Answer 26

If 2 or more different compounds are composed of the same 2 elements, then the ratio of the masses of the 2nd element combined with a certain mass of the 1st element is always a ratio of small whole numbers

Question 27

What is John Dalton’s explanation?

Answer 27

He reasoned that elements were composed of atoms & that only whole #’s of atoms can combine to form compounds

Question 28

What is Dalton’s Atomic Theory?

Answer 28

1). All matter is composed of small particles called atoms
2). Atoms of a given element are identical in size, mass, and other propertied differs from others
3). Atoms can’t be subdivided, created, or destroyed
4). Atoms of different elements combine to fore simple who number chemical compounds
5). In chemical ration, atoms are combined, separated, or rearranged

Question 29

Can atoms be divided into smaller particles?

Answer 29

Yes

Question 30

Does every atoms of an element have an identical mass?

Answer 30

NO

Question 31

Is all matter composed of atoms?

Answer 31

Yes

Question 32

Are atoms of any one element differ from another?

Answer 32

Yes

Question 33

Who discovered the electrons?

Answer 33

J.J. Thomspson

Question 34

Goldstein and Chadwick discovered what?

Answer 34

Proton and neutrons

Question 35

Equation for Unknown relative Abundance?

Answer 35

(Mass #1) (x [relative abundance]) + (Mass #2) (1-x[relative abundance]) = Atomic mass of the element

Then multiply by 100 to get percent but for the 2nd one do 1-x then multiply by 100

Question 36

Equation for Weighted Abundance?

Answer 36

(Mass #1) (abundance) + (Mass #2)(abundance)

Question 37

What is molar mass unit?

Answer 37

g/mol