Download Name Block Hon 1 Chemistry I – Ms. Elder Chapter 3 Atomic

Name
Hon 1 Chemistry I – Ms. Elder
Chapter 3 Atomic Structure
Block
3-1 Early Models of the Atom
3-2 Discovering Atomic Structure
3-3 Modern Atomic Theory
3-4 Changes in the Nucleus
3-1 Early Models of the Atom - What are atoms? What are the postulates of Dalton’s atomic theory?
Democritus

– 450BC
 Proposed that

 Including
 His beliefs were not accepted until the
 Was not accepted until




Water will always have 88.9% oxygen (O) and 11.1% hydrogen (H)
John Dalton (1766 – 1844)

 Studied past
of atoms and laws of matter
 Formed an
Dalton’s Atomic Theory of Matter
 Ea element is composed of



Atoms

 There are
wh means there are 118 different kinds of atoms.
 Atoms are like the
on this paper.
 If we broke it all apart, separated and organized the letters, you would find only 26 piles.
 But by taking letters from different piles we can create millions of very different words
 Just like words can be separated into letters,
 These separated atoms are called
 Think of all the words you could make with the letters A, D, and M….
Scanning Tunneling Microscope (STM)
 Produces
 Created in
Chemistry In Action (p93)
 Consumer Tip “100 Percent Natural”
Macroscopic vs Microscopic
 Macroscopic –


It is made of the leaves, branches, trunk, roots
 Microscopic –
 A leaf off a tree and the little veins that carry the nutrients through it
 Chemists make their observations in the
 It is the world
 In order to understand that world,
 Discoveries/Possibilities b/c of the study of atoms




3-2 Discovering Atomic Structure How is atomic structure related to electricity? What did cathode rays indicate about
atoms? What did Rutherford conclude from his alpha-scattering experiment?
Electric Charges
 Scientists couldn’t figure out why atoms of one element
 Michael Faraday (1791-1867) said that the structure of an atom
 Atoms contain particles that have
Benjamin Franklin
 An object will either have a
 2 like charges will


 2 opposite charges

 Franklin didn’t know where these charges came from
Cathode Rays and Electrons
 Electric current  Electricity from
 Studying
provide key to understanding
 Mid-1800s, began studying electric currents in

 Positive and negative

Negative =

Positive =
 Radiation travels from
 b/c radiation came from cathode end, called
and the tube a
Electrons


(1856-1940)
 Mass of
 0.000000000000000000000000000911 gram

(1868-1953)
Radioactivity
 Henry Becquerel (1852-1908)

 Uranium was
 Radioactivity:

discovered the elements of
were also radioactive
The Nuclear Atom
 Thompson said there were
(neg charge)
 Why is the atom neutral then?


Called this center the

Has a

 If the atom was the size of a football stadium, the nucleus would be
 Electrons would be smaller than Franklin Roosevelt’s
on the dime
3-3 Modern Atomic Theory What are the names and properties of the 3 subatomic particles? How can you determine
the # of protons, neutrons, and electrons in an atom/ion? What is an isotope? What is atomic mass?
Subatomic Particles
 We know atoms are made from
 Recently scientists have found even

,
,
,
, and others
 They don’t seem to impact

Physicists study them
The Structure of the Atom
 Nucleus
 Contains the

Protons =


Have the same but opposite
Neutrons =
 Electrons

charged – e-

– e- cloud
 Very

Size of Subatomic Particles
 Mass

 Has own unit  P+ and n0 =
, e- =
b/c so small
 Length
 Diameter = 0.100 – 0.500

Nanometer =
=
 If you drew a line across a penny (1.9 cm), you would
 If you lined up all

4 millionths of a meter
Atomic Numbers
 Henry Moseley (1887-1915)

 Discovered atoms of ea element
 Lead to the idea that
 Call this #

 Ea element has
 Can tell an element’s atomic # from
Neutral Atom
 The p+ are
 The e- are
 The atom is
 This means,
 For N, atomic # =

Means p+ =

Means e- =
Examples
 How many protons and neutrons in:
 Oxygen (O)
 Magnesium (Mg)
, you would only have a line
long
 Silicon (Si)
 What element has 11 protons?
Ions
 When an atom

, it will have a
, called
 Charge of ion =
 If a magnesium atom loses 2 e-, ionic form has a charge of:

#p+ - #e- =

It is important to add the
sign into the answer
 Also possible to have a

Some people write the charge with the +/-
 After you have calculated the charge, to write it with the element symbol,
 For our magnesium example:
Examples
 Write the chemical symbol for the ion w/:
 9 p+ and 10 e-
 13 p+ and 10 e 7 p+ and 10 e-
 How many p+ and e- are present in:
 S-2 ion
 Li+ ion
 Write the chemical symbol for the ion w/:
 12 p+ and 10 e-
 74 p+ and 68 e-
(2+)
Isotopes
 All atoms of the
, have
 They may not have the same

, we call them isotopes
 Most elements have at least
 1 usually more
than another
 In nature, it is usually a
 To tell isotopes apart, we use the
Mass Number
 Mass # =
 An atom w/ 17p+ and 18n0 would have an mass # of

Mass # =
 b/c 17 p+, tells us it is a

 A way to write the element symbol w/ atomic and mass #s would be:
Examples
 How many protons, neutrons, and electrons are in the following ions?
 Fe+2
 Al+3
 Se-2
 Write the complete chemical symbol for the ion w/
 21 p+, 24 n0, and 18 e-
 53 p+, 74 n0, and 54 e-
Atomic Mass

 Listed in the
Protons, Neutrons & Electrons
1) How many protons and electrons are present in an iron atom?
2) How many protons and electrons are present in a cadmium atom?
3) How many protons and electrons are present in a xenon atom?
4) How many protons and electrons are present in a barium atom?
5) How many protons and electrons are present in a chlorine atom?
6) What is the name of the element that has atoms that contain 2 protons?
7) What is the name of the element that has atoms that contain 39 protons?
8) What is the name of the element that has atoms that contain 47 protons?
9) What is the name of the element that has atoms that contain 98 protons?
10) What is the name of the element that has atoms that contain 78 protons?
11) Write the chemical symbol and charge for the ion with 20 protons and 18 electrons.
12) Write the chemical symbol and charge for the ion with 41 protons and 38 electrons.
13) Write the chemical symbol and charge for the ion with 8 protons and 10 electrons.
14) Write the chemical symbol and charge for the ion with 42 protons and 36 electrons.
15) Write the chemical symbol and charge for the ion with 9 protons and 10 electrons.
16) Write the chemical symbol and charge for the ion with 70 protons and 73 electrons.
154
17) How many protons, neutrons and electrons are present in
+3
63Eu ?
46
18) How many protons, neutrons and electrons are present in ? 22Ti+4 ?
123
19) How many protons, neutrons and electrons are present in ? 51 Sb-3
65
20) How many protons, neutrons and electrons are present in ?
+1
29Cu
263
21) How many protons, neutrons and electrons are present in ?
+2
106Sg
17
22) How many protons, neutrons and electrons are present in ?
8O
-2
183
23) How many protons, neutrons and electrons are present in ?
74W
+5
24) Write the complete chemical symbol for the ion with 90 protons, 143 neutrons and 88 electrons?
25) Write the complete chemical symbol for the ion with 62 neutrons, 42 electrons and 46 protons.
26) Write the complete chemical symbol for the ion with 36 electrons, 45 neutrons and 35 protons.
27) Write the complete chemical symbol for the ion with 19 protons, 18 electrons and 21 neutrons.
28) Write the complete chemical symbol for the ion with 1 proton, 2 neutrons and 0 electrons.
29) Write the complete chemical symbol for the ion with 40 protons, 37 electrons and 52 neutrons.
30) Write the complete chemical symbol for the ion with 36 electrons, 34 protons and 45 neutrons.
Protons, Neutrons, and Electrons Practice Worksheet
Atomic
symbol
Atomic
number
Protons
B
Neutrons
Electrons
Atomic
mass
6
11
24
31
37
39
29
89
35
43
100
Pb
207
102
89
Mo
70
225
53
81
206
100
159
No
261
Yb
172
106
159
3-4 Changes in the Nucleus What changes accompany nuclear reactions? What is radioactivity?
Nuclear Reactions
 Change the
 Produces
radiation
 Alpha and beta radiation comes from
 Almost all atoms have
 Not
 Radioactivity
– good its rare to find in nature
 Why are some more stable than others?

 Some combinations cause
 In nucleus, p+ and n0 are
 How do p+ stay together in the small space if like charges repel?


Can only be found in
 Neutrons act like
along with the strong nuclear force
 Pattern of stability
 Atomic # 1-20 –
, = # of
 Beyond 20 p+ - more n0 needed to
 Atomic # above 83 –

No # of n0 will
 Atoms unstable if too many or too few
 Atoms w/ too many
Types of Radioactive Decay
 Alpha (α)
 Alpha particles have
 Identical to
nucleus
 Travel only
 Easily stopped by
 Usually doesn’t pose a health threat unless
 Beta (β)

(not the ones around the nucleus)
 Comes from
 A neutron changes

p+ stays in

e- (beta particle) is
 100 times more

Able to penetrate 1-2 mm of

Able to pass through
 Gamma (γ)
 Very energetic
 Doesn’t have
 More
 Able to penetrate

 Stopped only

 When an atom emits radiation,
 Called decay b/c
 The best way to understand the decay is
Partner Activity
 Look at Figure 3-30 and answer the questions
 Would this protective suit protect the worker from alpha radiation?
 Why would a person working w/ alpha radiation also need to be concerned w/ gamma radiation?
 Would protective clothing such as this stop gamma radiation from penetrating the worker’s skin?