Atomic Theory

Question 1

Atoms

Answer 1

Small, hard, indivisible particles mad up of the same material but in different shapes and sizes

Question 2

Democritus theory

Answer 2

Matter cannot be divided into smaller pieces continuously … Theory was ignored and forgotten

Question 3

Atomos

Answer 3

Smallest piece, meaning “not to be cut”, changes in matter result from arrangement of grouping of atoms

Question 4

Aristotle and Plato’s theory

Answer 4

Everything is made up of earth, air, fire, and water .. WRONG

Question 5

Law of definite proportion

Answer 5

Joseph Proust… Elements composition of a pure substance never varies

Question 6

John Dalton **

Answer 6

Theory that atoms are building blocks of matter

Question 7

Bullard ball model

Answer 7

Theorized atoms were like Bullard balls - a single solid mass

Question 8

Democritus

Answer 8

Matter that was composed of empty space

Question 9

John dalton postulates

Answer 9

1- atoms of the same element are identical in mass and other properties -INCORRECT
2- chemical reactions occur when atoms are separated, joined, or rearranged. However elements never change into other elements
3- atoms chemically combine in simple whole number ratios to form compound

Question 10

J.J. Thompson

Answer 10

Plum pudding model… Cathode ray

Question 11

Plum pudding model

Answer 11

• Negative electrons (plum)
  were embedded in a uniform sphere with a positive charge (pudding)
• streams if negatively charged particles were found to emanate energy from cathode ray

Question 12

Cathode ray

Answer 12

Able to measure charge - to - mass ratio to find the mass of a single cathode ray particle

Question 13

Millikan

Answer 13

Determined charge of electron… Was within 1% of the accepted value (-1) … Used charged and charge to mass ratio to determine mass

Question 14

Mass of electron

Answer 14

9.11 x 10^(-28) g = 1/1840 of hydrogen atom

Fraction of mass of proton/ neutron

Question 15

Radioactivity

Answer 15

Spontaneous emission of radiation by an atom … First observed by Henri Becquerel

Question 16

Alpha particles

Answer 16

+ , large mass

Question 17

Beta particles

Answer 17

• , negligible mass

Question 18

Y rays

Answer 18

Neutral

Question 19

Rutherford’s gold foil experiment

Answer 19

Test “plum pudding”
Fired alpha particles at gold foil
Thought most alpha particles would go straight through
Unexpected results

Question 20

Gold foil results

Answer 20

Most are in deflected and went straight through… Some particles were scattered

Question 21

Gold foil conclusion

Answer 21

1- atoms in foil consists of MOSTLY EMPTY SPACE ,

2- must be hitting and object with a very DENSE MASS and it must be POSITIVELY charged

Question 22

Henry Mosley

Answer 22

Discover it is the number of protons in the nucleus that makes each element unique (ATOMIC NUMBER)

Question 23

Subatomic particle

Answer 23

Protons, neutrons, & electrons

Question 24

Proton

Answer 24

+ , found in nucleus , balanced with electrons

Question 25

Electrons

Answer 25

- , found in space around nucleus

Question 26

Amber

Answer 26

Material discovered that exhibits effects of electrical charging

Question 27

Neutrons

Answer 27

Neutral , found in nucleus, mass almost exact to that or a proton

Question 28

AMU

Answer 28

Atomic mass unit

Question 29

12 C 6

Answer 29

``` C= symbol of element 12 = mass number (protons + neutron) 6= atomic number / number of proton ```

Question 30

Ion

Answer 30

Atom or molecule with an electric charge .. Results from gain/ loss of 1+ electrons... Positive ions have lost electrons & negative ions have gained an electron

Question 31

Isotopes

Answer 31

Elements with the same number of protons and a diff number of neutrons I.e C-14

Question 32

Average mass unit

Answer 32

Mass of an atom in AMU ... 1.6605402 x 10 ^ (-27) kg ... Atoms have very little mass... Equals to 1/12 of carbon mass ... Weighted mass

Question 33

Avg mass unit calculation

Answer 33

(Mass isotope 1) (% abundance) / 100 + (mass isotope 2) (% abundance) /100 Get the number on periodic table

Question 34

Mass spectrometry

Answer 34

Analytical technique that measures the mass-to-charge ration of changed particles ie. vaporization,