Chemistry Chapter 4

Front 1

What did Greek philosophers first believe all matter was composed of?

Back 1

1.air
2.earth
3.fire
4.water

Front 2

Democratis

Back 2

1. first to propose idea of atom
2. matter is composed of empty space that atoms move through
3. atoms are solid, undivisible
4. diff. atoms are diff. sizes
5. diff. properties due to size, shape, motion
6. changes in matter caused by diff. grouping of atoms

Front 3

Aristotle

Back 3

1. did not believe in atoms
2. did not agree with Democratis
3. did not believe empty space existed
4. believed all matter was continuous

Front 4

Who was John Dalton?

Back 4

(1776-1844) English school teacher who began development of modern atomic theory

Front 5

What was Dalton's Atomic Theory?

Back 5

1. all matter is composed of atoms
2. atoms in an element are identical, different atoms make different elements
3. atoms cannot be divided, created, or destroyed
4. atoms combine in simple whole number ratios
5. in a chemical reaction, atoms are separated, combined, rearranged

Front 6

Alchemists (Middle Ages)

Back 6

First true chemist, tried to change common metals into gold, his experiments revealed the properties of matter

Front 7

William Crookes

Back 7

Created the "CRT" (Cathode Ray Tube)

Front 8

Atom

Back 8

Smallest particle of an element that still retains the properties of that element

Front 9

Nanotechnology

Back 9

Molecular manufacturing - the atom by atom building of machines the size of atoms

Front 10

Describe the Cathode Ray Tube Experiment

Back 10

A tube filled with low pressure gas. A negative cathode was on one side, and a positive anode on the other. One electrode was connected to the cathode and one to the anode. A beam of light was seen in the tube.

Front 11

Cathode Ray

Back 11

Ray traveling form cathode to anode within the tube (later termed radiation)

Front 12

What did William Crookes conclude after his cathode ray experiment?

Back 12

1. A "cathode ray" was a stream of negatively charged particles that moved from -cathode to +anode
2. All matter has a negative particle

Front 13

J.J. Thomson

Back 13

(1890's) Did a series of CRT experiments to determine nature of these green glowing particles. Discovered proton and electron.

Front 14

Describe Thomson's Experiment

Back 14

-when particles hit the flourescent screen, the spot glowed green
-bend ray with magnet- will always flow to opposite charged electrode
-he called this small, negative particle and electron

Front 15

What did Thomson conclude after his cathode ray experiment?

Back 15

1. figured charge to mass ratio, found mass electron much less than H
2. showed atoms were divisible
3. atoms are neutral, so if electrons exist, knew a positive particle must exist - switched position of anode and cathode and found positive ray - positive charge particle called proton

Front 16

Milikan's Oil Drop Experiment

Back 16

Balanced a single oil drop in mid air using electrical and magnetic fields-measured E used to calculate amount of charge of electron (1-)

Front 17

Thomson's Plum Pudding Atomic Model

Back 17

-Electrons distributed inside uniformly positively charge protons
-Solid sphere

Front 18

Rutherford's Gold Foil Experiment

Back 18

-Beam alpha particles aimed at gold foil sheet, flash when struck by a particle
-Because uniform positive charge, thought alpha particles would experience only minor deflections

Front 19

What were the results to Rutherford's Goil Foil Experiment?

Back 19

Most alpha particles passed straight through, others were deflected at large angles

Front 20

What did Rutherford conclude about his gold foil experiment?

Back 20

Most of atom is empty space through which electrons move around nucleus. Negatively charged electrons held within atom by attraction to positive nucleus.

Front 21

What was the problem to Rutherford's conclusion?

Back 21

Protons and electrons will attract causing atom to collapse

Front 22

1920 Rutherford's Refined Atomic Theory

Back 22

Nucleus's number of protons is equal to the number of electrons orbiting in the empty space around the nucleus

Front 23

Nucleus

Back 23

Central, dense region that contains atom's positive charge and mass

Front 24

James Chadwick

Back 24

Rutherfor's co-worker discovered neutron - collectively found three subatomic particles

Front 25

Proton

Back 25

Subatomic particle with an equal but opposite charge to an electron (1+)

Front 26

What did James Chadwick discover about the electron?

Back 26

-outside nucleus
-very small mass
-negative charge

Front 27

What did James Chadwick discover about the proton?

Back 27

-inside nucleus
-massive (as compared to electron)
-positive charge

Front 28

What did James Chadwick discover about the neutron?

Back 28

-inside nucleus
-no charge
-same mass as proton

Front 29

Electrons and protons have _______ but opposite charges.

Back 29

Equal

Front 30

What compose the mass of an atom?

Back 30

Protons and neutrons in nucleus

Front 31

Quarks

Back 31

Alpha subatomic particles forming protons and neutrons

Front 32

Atomic Number

Back 32

-number of protons
-always a whole number because atoms are neutral

Front 33

What is the rule between the number of protons and the number of electrons in an atom?

Back 33

They are always equal

Front 34

Mass Number

Back 34

Number of protons and neutrons

Front 35

How can you find the neutrons in an atom?

Back 35

Mass number
-Atomic number
----------------------
# neutrons

Front 36

Isotope

Back 36

Atoms with the same number of protons, but different number of neutrons

Front 37

What do isotopes produce and where are they most commonly found?

Back 37

Produce unstable nucleus radioactive decay, very common in nature

Front 38

In an isotope which one is radioactive?

Back 38

The heavier one

Front 39

The Atomic Standard

Back 39

Carbon-12, carbon has a mass of exactly 12 AMU 6 protons and 6 neutrons

Front 40

What does 1 AMU equal?

Back 40

1/12 Carbon = 1 gram on periodic table

Front 41

What is the formula between AMU, protons, and neutrons?

Back 41

1 AMU = Mass 1 proton = mass 1 neutron

Front 42

Atomic Mass

Back 42

Weighted average mass of the isotopes of that element

Front 43

How do you calculate average atomic mass?

Back 43

%abundance x mass
+%abundance x mass
---------------------------------
average atomic mass

Front 44

Nuclear Reactions

Back 44

Reactions that involve a change in an atoms nucleus

Front 45

Radiation

Back 45

Rays and particles emitted by radioactive material because nuclei are unstable

Front 46

Radioactive Decay

Back 46

Unstable nuclei lose energy by emitting radiation

Front 47

What are the three different types of radiation?

Back 47

1. Alpha
2. Beta
3. Gamma

Front 48

Alpha Radiation

Back 48

-Deflected toward negatively charged plate
-Made of alpha particles, 2+ charge

Front 49

What is the symbol for an alpha particle?

Back 49

42 He

Front 50

Beta Radiation

Back 50

-Deflected toward positively charged plate
-Made of beta particles, fast moving electrons with a 1- charge

Front 51

What is the symbol for a beta particle?

Back 51

0-1 B

Front 52

Gamma Radiation

Back 52

-Not deflected
-Made of gamma rays, high energy radiation with no mass
-Accompanies alpha and beta radiation

Front 53

What is the symbol for gamma rays?

Back 53

00 Y

Front 54

What are the two types of Radioactivity?

Back 54

1. change in nuclear mass
2. does not change nuclear mass