Atomic Theory/ Masses of Atoms ( Chap. 17: Sec. 1/2)

Question 1

Atom

Answer 1

Atom: the smallest piece of matter that still retains the property of the element

Question 2

Nucleus

Answer 2

Nucleous: Small positively charged center of an atom where protons and neutrons are found

Question 3

Protons

Answer 3

Protons: are particles with a positive charge

Question 4

Neutrons

Answer 4

Neutrons: Particles with no charge

Question 5

Electrons

Answer 5

Electrons: Particles with a negative charge

Question 6

Quarks

Answer 6

Quarks: Smaller Particles that make up protons and nuetrons

Question 7

Electron Cloud:

Answer 7

Electron Cloud: Are around the nucleus of an atom where its electrons are most likely to be found.

Question 8

John Dalton’s theory

Answer 8

John Dalton came up with the atomic theory on experimental evidence derived from measuring the mass of various types of elements such as carbon.

Question 9

Thompson

Answer 9

Discovered Electron (-) Cathode Ray Tube

Question 10

Cathode Ray Tube

Answer 10

• Filled with gas to examine the atom
• A beam moves from a negatively charged electrode to a positively charged electrode
• The beam acts acts as a stream of particles
• Since the particles are coming from a negatively charged electrode the stream must also be negative
• When Thompson moved a negatively charged plate toward the tube the beam beam bent away
• when he put a positive charged plate towards the beam it attracted
• Negative attracts negative

Question 11

Rutherford

Answer 11

discovered protons

Question 12

Gold Foil Experiments

Answer 12

-Used Alpha (+ charged) particles that Rutherford directed toward at a piece of gold foil
-Found that some of the alpha particles bounced back towards the source because (+ repels +)
Conclusions
-he confirmed his hypothesis that the atom contains empty space
-He confirmed the existence of negatively charged particles
-He discovered the proton which was contained in a small dense nucleus

Question 13

Chadwick

Answer 13

Discovered The Neutron

Question 14

The ratio of atomic masses is

Answer 14

4:1

Question 15

The Removal of the paraffin block showed that there was a ____ of the amount of radiation detected giving evidence to the existence of ____

Answer 15

The Removal of the paraffin block showed that there was a doubling of the amount of radiation detected giving evidence to the existence of neutrons

Question 16

Thompson’s Model of the Atom is mostly not correct because

Answer 16

the atom is mostly empty space

Question 17

Niels Bohr

Answer 17

proposed the model of the atom where electrons travel in a fixed orbit.

Question 18

It is impossible to tell the location of both ___ & ___

Answer 18

location of the electron in an atom and its motion

Question 19

All Atoms of an ___ have the same mass

Answer 19

element

Question 20

Atoms can be distinguished by their ___

Answer 20

mass

Question 21

Where is most of the mass of an atom

Answer 21

Nucleus

Question 22

Which Subatomic Particle is the least massive and by how much?

Answer 22

Electron; x2000

Question 23

How do scientists describe the masses of subatomic particle?

Answer 23

Atomic Mass Unit

Question 24

1 proton= 1 Neutron

Answer 24

1.67x 10^-24

Question 25

What subatomic particle identifies an element?

Answer 25

Proton

Question 26

Isotopes

Answer 26

Some elements have different amounts of Neutrons called Isotypes.