Download atomic regents review

The Physical Setting
Chemistry
Jerry Deutsch
1
New York State
Education Department
Core Curriculum
http://www.emsc.nysed.gov/ciai/mst/pub/chemist.pdf
2
I. Atomic Concepts
3
The modern model of the atom
has evolved over a long period
of time through the work of
many scientists. (3.1a)
 Democritus – matter is made up of particles called atoms
 Dalton – atoms of the same element are alike – solid
indivisible spheres
 Thomson – discovers electrons – plum pudding model
 Rutherford – gold foil experiment – discovers heavy, +
charge nucleus – mostly empty space
 Bohr – orbital model of electrons
J Deutsch 2003
4
J Deutsch 2003
5
Regents Question: 08/02 #1
Subatomic particles can usually pass undeflected
through an atom because the volume of an atom
is composed of
(1) an uncharged nucleus
(2) largely empty space
(3) neutrons
(4) protons
J Deutsch 2003
6
Regents Question: 01/03 #62-64
One model of the atom states that atoms are tiny
particles composed of a uniform mixture of positive
and negative charges. Scientists conducted an
experiment where alpha particles were aimed at a
thin layer of gold atoms.
Most of the alpha particles passed directly through
the gold atoms. A few alpha particles were deflected
from their straight-line paths. An illustration of the
experiment is shown below.
J Deutsch 2003
7
Regents Question cont’d
•Most of the alpha particles passed directly
through the gold atoms undisturbed. What
does this evidence suggest about the structure
of the gold atoms?
Most of the atom is empty space.
•A few of the alpha particles were deflected.
What does this evidence suggest about the
structure of the gold atoms?
There is central + charge. The nucleus is +.
•How should the original model be revised
based on the results of this experiment?
J Deutsch 2003
The atom is not a uniform mixture of + and - charge.
Positive charge is located in a heavy central mass.
8
Regents Question: 06/03 #67
John Dalton was an English scientist who
proposed that atoms were hard, indivisible
spheres. In the modern model, the atom has a
different internal structure.
•Identify one experiment that led scientists to
develop the modern model of the atom.
Rutherford’s gold foil experiment
J Deutsch 2003
9
Regents Question cont’d
John Dalton was an English scientist who
proposed that atoms were hard, indivisible
spheres. In the modern model, the atom has a
different internal structure…
•Describe this experiment.
Rutherford shot alpha particles a piece of gold foil.
Most of the alpha particles went through, some were
deflected and some were reflected.
•State one conclusion about the internal
structure of the atom, based on this
experiment.
J Deutsch 2003
Most of the atom is empty space.
10
Each atom has a nucleus, with
an overall positive charge,
surrounded by one or more
negatively charged electrons.
(3.1b)
J Deutsch 2003
11
Subatomic particles contained in
the nucleus include protons and
neutrons. (3.1c)
 Particles in the nucleus (protons and neutrons) are
called nucleons
 The mass of the atoms is concentrated in the
nucleus
 Electrons are not found in the nucleus, they orbit
the nucleus.
 The net charge of the nucleus is positive (+)
J Deutsch 2003
12
The proton is positively
charged, and the neutron has
no charge. The electron is
negatively charged. (3.1d)
Mass
Charge
J Deutsch 2003
13
Regents Question: 01/03 #1
Which statement best describes electrons?
(1) They are positive subatomic particles and are found in
the nucleus.
(2) They are positive subatomic particles and are found
surrounding the nucleus.
(3) They are negative subatomic particles and are found in
the nucleus.
(4) They are negative subatomic particles and are found
surrounding the nucleus.
J Deutsch 2003
14
Regents Question: 06/02 #58-60
In the modern model of the atom, each atom is composed of
three major subatomic (or fundamental) particles.
•
Name the subatomic particles contained in the nucleus of
the atom.
Proton and neutron
•
State the charge associated with each type of subatomic
particle contained in the nucleus of the atom.
Proton is positive and the neutron is neutral
•
What is the net charge of the nucleus?
Positive
J Deutsch 2003
15
Regents Question: 06/03 #2
Which subatomic particle has no charge?
(1) alpha particle
(2) beta particle
(3) Neutron
(4) electron
J Deutsch 2003
16
Protons and electrons have
equal but opposite charges.
The number of protons equals
the number of electrons in an
atom. (3.1e)
# of protons = # of electrons
Therefore, atoms are electrically neutral.
J Deutsch 2003
17
The mass of each proton and
each neutron is approximately
equal to one atomic mass unit.
An electron is much less
massive than a proton or a
neutron. (3.1f)
Mass
Charge
J Deutsch 2003
18
The atomic number for an element
cannot change but its mass number can.
 Atomic Number
– The number of protons in the nucleus of an atom
– Determines which element
 Mass Number
– The number of nucleons (protons + neutrons)
 # neutrons = mass # - atomic #
J Deutsch 2003
19
Regents Question: 06/02 #33
The number of neutrons in the nucleus of an atom can be
determined by
(1) Adding the atomic number to the mass number
(2) Subtracting the atomic number from the mass number
(3) Adding the mass number to the atomic mass
(4) Subtracting the mass number from the atomic number
J Deutsch 2003
20
Regents Question: 06/03 #1
The atomic number of an atom is always equal to the
number of its
(1) protons, only
(2) neutrons, only
(3) protons plus neutrons
(4) protons plus electrons
J Deutsch 2003
21
Regents Question: 08/02 #4
What is the total number of protons in the
nucleus of an atom of potassium-42?
(1) 15
(2) 19
(3) 39
The mass number (42) is not
necessary to find the number of
protons.
(4) 42
J Deutsch 2003
22
Regents Question: 06/03 #36
The nucleus of an atom of K-42 contains
(1) 19 protons and 23 neutrons
(2) 19 protons and 42 neutrons
(3) 20 protons and 19 neutrons
(4) 23 protons and 19 neutrons
J Deutsch 2003
23
In the wave-mechanical
model (electron cloud model),
the electrons are in orbitals,
which are defined as the
regions of the most probable
electron location (ground
state). (3.1h)
An orbital is the area of highest
probability of finding an electron.
J Deutsch 2003
24
Regents Question: 06/03 # 5
The region that is the most probable location of an
electron in an atom is
(1) the nucleus
(2) an orbital
(3) the excited state
(4) an ion
J Deutsch 2003
25
Regents Question: 06/02 #2
The modern model of the atom shows that electrons are
(1) orbiting the nucleus in fixed paths
(2) found in regions called orbitals
(3) combined with neutrons in the nucleus
(4) located in a solid sphere covering the nucleus
J Deutsch 2003
26
Each electron in an atom has
its own distinct amount of
energy. (3.1i)
When electrons are in their lowest energy
state, it is called the ground state
The ground state for Na is 2-8-1
J Deutsch 2003
27
Electron Configuration tells us how
many electrons in each principal
energy level (shell).
 Atomic Number = 7
 Mass Number = 14
 7 protons
 7 neutrons
 7 electrons
 Electron
configuration: 2-5
J Deutsch 2003
28
The electron configuration for the
ground state of an atom is given
on the Periodic Table of the
Elements.
Electron Configuration
J Deutsch 2003
29
Regents Question: 06/02 #1
What is the electron configuration of a sulfur atom in the
ground state?
(1) 2-4
(2) 2-6
(3) 2-8-4
(4) 2-8-6
Look at the Periodic Table of the Elements
If you do not know the symbol for sulfur, check Table S
J Deutsch 2003
30
When an electron in an atom
gains a specific amount of
energy, the electron is at a
higher energy state (excited
state). (3.1j)
Possible excited states for Na are:
2-7-2
1-8-2
J Deutsch 2003
31
When an electron returns
from a higher energy state to
a lower energy state, a
specific amount of energy is
emitted. This emitted energy
can be used to identify an
element. (3.1k)
Emission Spectrum
J Deutsch 2003
32
J Deutsch 2003
33
Regents Question: 01/03 # 2
During a flame test, ions of a specific metal are heated in
the flam of a gas burner. A characteristic color of light
was emitted by these ions in the flame when the
electrons
(1) Gain energy as they return to lower energy levels
(2) Gain energy as they move to higher energy levels
(3) Emit energy as they return to lower energy levels
(4) Emit energy as they move to higher energy levels
J Deutsch 2003
34
Regents Question: 06/03 # 3
When the electrons of an excited atom return to a
lower energy state, the energy emitted can result
in the production of
(1) alpha particles
(2) Isotopes
(3) protons
(4) spectra
J Deutsch 2003
35
Regents Question: 06/03 #51-52
Base your answers to the next two questions on the
electron configuration table shown below.
•
What is the total number of valence electrons in an
atom of electron configuration X?
2
•
Which electron configuration represents the excited
state of a calcium atom?
2-8-7-3
Element
X
Y
Z
J Deutsch 2003
Electron
Configuration
2 –8 –8 –2
2 –8 –7 –3
2 –8 –8
36
The outermost electrons in an
atom are called the valence
electrons. In general, the
number of valence electrons
affects the chemical
properties of an element.
(3.1l)
The ground state for Na is 2-8-1
•The valence shell is the third shell.
•The valence shell contains 1 electron.
J Deutsch 2003
37
Regents Question: 08/02 #2
What is the total number of electrons in the
valence shell of an atom of aluminum in the
ground state?
(1) 8
(2) 2
(3) 3
(4) 10
J Deutsch 2003
38
Regents Question: 06/02 #31
In which shell are the valence electrons of the elements
in Period 2 found?
(1) 1
(2) 2
(3) 3
(4) 4
J Deutsch 2003
39
Atoms of an element that
contain the same number of
protons but a different number
of neutrons are called
isotopes of that element.
(3.1m)
Isotopes of Hydrogen
J Deutsch 2003
1H
– protium
1 proton
0 neutron
2H
– deuterium
1 proton
1 neutron
3H
– tritium
1 proton
2 neutrons
40
Regents Question: 01/03 #9
An atom of carbon-12 and an atom of carbon-14 differ in
(1) Atomic number
(2) Atomic mass
(3) Nuclear charge
(4) Number of electrons
Carbon-12 and carbon-14 are isotopes.
J Deutsch 2003
41
Regents Question: 06/02 #4
All the isotopes of a given atom have
(1) the same mass number and same atomic number
(2) the same mass number but different atomic numbers
(3) different mass numbers but the same atomic number
(4) different mass numbers and different atomic number
J Deutsch 2003
42
Regents Question: 06/02 #9
Atoms of the same element that have different numbers
of neutrons are classified as
(1) Charged atoms
(2) Charged nuclei
(3) Isomers
(4) Isotopes
J Deutsch 2003
43
The average atomic mass of
an element is the weighted
average of the masses of its
naturally occurring isotopes.
(3.1n)
Isotope Mass Abundance
Calculation
12C
12
98.89%
12 x .9889 =
13C
13
1.108%
13 x 0.01108 = 0.1440
Atomic Mass (weighted average)
J Deutsch 2003
11.87
12.01 amu
44
Atomic mass is found on the
Periodic Table of the Elements
J Deutsch 2003
45
Regents Question: 06/03 # 4
The atomic mass of an element is calculated using the
(1) atomic number and the ratios of its naturally occurring
isotopes
(2) atomic number and the half-lives of each of its
isotopes
(3) masses and the ratios of its naturally occurring
isotopes
(4) masses and the half-lives of each of its isotopes
J Deutsch 2003
46
Regents Question: 01/03 #36
Hydrogen has three isotopes with mass numbers of 1, 2,
and 3 and has an average atomic mass of 1.00794
amu. This information indicates that
(1) Equal number of each isotope are present
(2) More isotopes have an atomic mass of 2 or 3 than 1
(3) More isotopes have an atomic mass of 1 rather than 2
of 3
(4) Isotopes have only an atomic mass of 1
J Deutsch 2003
47
Regents Question: 01/03 #3
In which list are the elements arranged in order of
increasing atomic mass?
(1) Cl, K, Ar
(2) Fe, Co, Ni
(3) Te, I Xe
(4) Ne, F, Na
Look for the masses on the periodic
table of the elements.
J Deutsch 2003
48
Part A questions
J Deutsch 2003
49
J Deutsch 2003
50
J Deutsch 2003
51
Part B-1 questions
J Deutsch 2003
52
J Deutsch 2003
53
J Deutsch 2003
54
Part B-2 questions
J Deutsch 2003
55
J Deutsch 2003
56
Part C questions
J Deutsch 2003
57
J Deutsch 2003
58