Study Guide

1
Study Guide
2
Study Guide

• Daltons model of the atom

3
Study Guide

• Daltons model of the atom
• Hard, round, and unbreakable like a billiard
  ball.

4
Study Guide
Thompsons model of the atom
5
Study Guide

• Thompsons model of the atom
• Small, negatively charged electrons scattered
  like chocolate chips throughout a positively
  charged cookie.

6
Study Guide
Rutherfords model of the atom
7
Study Guide
Rutherfords model of the atom Mostly empty
space with a small, hard, positive nucleus
surrounded by even smaller negatively charged
electrons.
8
How did Thompson figure out that electrons were
smaller than atoms?
9

• How did Thompson figure out that electrons were
  smaller than atoms?
• He used a cathode ray tube
• Shot a beam of electrons
• Deflected the beam with a magnet
• Knew how hard the magnet pulled
• Saw how far beam was defected
• Calculated mass from those numbers

10
How did Rutherford figure out that the nucleus
was small and hard?
11

• How did Rutherford figure out that the nucleus
  was small and hard?
• Shot alpha particles at gold foil
• Most particles went right through
• Therefore atoms must be mostly empty space
• A few particles bounced back
• Therefore atoms must have something small and
  hard in the middle.

12
Study Guide
Atomic number
13
Study Guide
Atomic number Number of protons in an element.
14
Study Guide
Atomic mass
15
Study Guide
Atomic mass Average mass of atoms of an element.
(Not necessarily a whole number.)
16
Study Guide
AMU
17
Study Guide
AMU Atomic mass unit. 1/12 the mass of a carbon
atom.
18
Study Guide
Mass number
19
Study Guide
Mass number The exact number of protons
neutrons in a specific atom. (Must be a whole
number.)
20
Study Guide
Isotope
21
Study Guide
Isotope At atom with a different number of
neutrons than other atoms of the same element.
22
Study Guide
Abundance
23
Study Guide
Abundance The number of atoms of one isotope
the total number of atoms of that element.
24
Study Guide
Nuclear reaction
25
Study Guide
Nuclear reaction The nucleus of an atom gains or
loses protons and becomes a different element.
26
Study Guide
Radioactive decay
27
Study Guide
Radioactive decay One kind of nuclear
reaction. The nucleus emits alpha or beta
particles and sometimes gamma rays.
28
Study Guide
Alpha particle
29
Study Guide
Alpha particle Two protons and two neutrons. It
is the same thing as a helium nucleus, with a
charge of 2.
30
Study Guide
Beta particle
31
Study Guide
Beta particle An electron, with a charge of -1.
32
Study Guide
Gamma ray Pure energy with no mass and no charge.
33
How can one element turn into a different element?
34

• How can one element turn into a different
  element?
• Only by changing the number of protons.
• Emitting an alpha particle decreases atomic
  number by two.
• Emitting a beta particle increases atomic number
  by one.