Download Unit 2 - The Atom 1-3.key

The Atom & Periodic
Table
Unit 2
Topics 1-3
Development of the Atomic Model
Topic 1
•
What do you think of when you hear the word
‘atom’?
Lab: Black Box
Atoms are so small we have special microscopes
to see them.
pictures of groups of
carbon
were MODEL
TOPIC 1These
– DEVELOPMENT
OF
THEatoms
ATOMIC
EXPLAIN
taken with a TEM (Tunneling Electron
Microscope)
and an
mallest particle
ofsmall
an element
that(Atomic
retains Force
its properties.
How
isAFM
an
atom?
Microscope).
s are so small we have special microscopes
Notice the scale bar (small black line in lower
e them.
right of picture). That line represents 2 nm
(that’s 2 nanometers.)
e pictures of groups of carbon atoms were If one nanometer equals 1x10-9 meters…
with a TEM (Tunneling Electron
oscope) and an AFM (Atomic Force
oscope).
AFM
2 nm
Then 62,500,000 of these pictures would fit in
one meter! That’s REALLY small!!
Important Experiments You Need to Know:
TEM
Notice the scale bar (small
black line in lower
-9
One nanometer equals 1x10 meters.
Discovering Electrons – right of picture). That line represents 2 nm
(that’s 2 nanometers.)
Negative Charge
-9 in one meter!
Then 62,500,000 of
these
pictures
would
fit
If one
nanometer
equals
1x10
meters…
Thomson (1897):
Experimented with Cathode
Then 62,500,000 of these pictures would fit in
Ray Tubes (CRTs)
Democritus's Atomic Theory
The smallest piece of matter is indivisible (atomos,
which means 'not to be cut')
Atoms:
• small
• hard particles
• made of the same material
• always moving
• capable of joining together
Dalton’s Atomic Theory (1808)
Matter is composed of extremely small particles called
atoms, which cannot be subdivided, created, or
destroyed.
Thompson’s Atomic Theory (1904)
•
electrons (plums) evenly distributed throughout a
positively charged ‘pudding’.
Rutherford’s Atomic Theory (1911)
Gold Foil Experiment
Expected vs. Actual
Rutherford’s Atomic Theory (1911)
Gold Foil Experiment - Results
1. Atoms are MOSTLY EMPTY SPACE
2. In the atom is a DENSE, POSITIVELY CHARGED
NUCLEUS
Bohr’s Atomic Theory (1913)
Planetary Model
Atoms travel in
specific orbits
around the
nucleus.
Quantum Mechanical (Modern) Theory
Electrons travel in diffuse
clouds around the nucleus
(orbitals)
13) An
atomsymbol
of oxygen
is in an excited
state. with
Whenaan
electron
this atom moves from the third
29)
Which
represents
a particle
total
of 10in
electrons?
shell to the second shell, energy is
1) Al
2) N3+
3) N
4) Al3+
1) absorbed by the electron
3) emitted by the electron
57) 2)
The
modern
model
of
the atom is were
based conducted
on the work
ofdetermine
emitted
the nucleus
4) toabsorbed
by the
30)
In
the
earlyby1900s,
experiments
thenucleus
structure of the atom. One o
14)
these
involved
bombarding
gold
with
alphainparticles.
alpha particles
1) many
overofavalence
short
period
of time
What
isexperiments
thescientists
total number
electrons
in anfoil
atom
of sulfur
the groundMost
state?
passed
Some,
however,
deflected at various
2) 6one directly
scientistthrough
over a short
period
of time
1)
2)the
8 foil.
3) were
3
4) 4 angles. Based on th
15)
In the box below, draw a Lewis electron-dot diagram of a selenium atom in the ground state.
two conclusions
alpha
particle
experiment,
state
that were made concerning the structure of a
3) many
scientists
over a long
period
of time
atom.
4) one scientist over a long period of time
Regents Practice
58) In the wave-mechanical model, an orbital is a region of space in an atom where there is
1) a high probability of finding an electron
31) The
the atom
shows
that
electrons are
2) amodern
circularmodel
path inofwhich
neutrons
are
found
1)
in regions
orbitals are found
3) found
a circular
path in called
which electrons
4) orbiting
a high probability
of finding
a neutron
2)
the nucleus
in fixed
paths
located in
sphere
59) 3)
An electron
hasa asolid
charge
of covering the nucleus
4)
with neutrons
inathe
nucleus
1) combined
+1 and a smaller
mass than
proton
3) -1 and a smaller mass than a proton
How many electrons are contained in an Au3+ ion?
2) +1 and the
mass
as a proton
4) has
-1 and the same mass as a proton
32) 1)
Compared
to asame
calcium
atom,
82
2)
197 the calcium ion Ca
3) 2+
76
4) 79
16)
60) What
Which
is based
on the "gold
experiment"
the protons
resulting model of the atom?
1)
more
3) and
more
17)
is conclusion
theelectrons
total number
of neutrons
in anfoil
atom
of aluminum-27?
1) fewer
An atom
has hardly any empty space, and the nucleus
has a negative
charge.
2)
protons
4) fewer
electrons
2) An atom is mainly empty space, and the nucleus has a negative charge.
33) When a lithium atom forms an Li+ ion, the lithium atom
3) An atom
is electron
mainly empty
and theshell
nucleus
a positive
charge.
18) Compared
to an
in the space,
first electron
of an has
atom,
an electron
in the third shell of
1)
loses
a proton
3) gains
an electron
4) same
An atom
has
has a positive
charge.
the
atom
hashardly any empty space, and the nucleus
2) less
gains
a proton
4) mass
loses an electron
1)
mass
3) less
4) more energy
Questions
61energy
through 63 refer2)to more
the following:
19)
In the modern wave-mechanical model of the atom, the orbitals are regions of the most probable
location
of model of the atom, each atom is composed of three major subatomic (or fundamental)
In the
modern
1) electrons
2) protons
3) positrons
4) neutrons
particles.
20)
Which electron transition represents a gain of energy?
1) from 2nd to 3rd shell
3) from 3rd to 1st shell
2) from 2nd to 1st shell
4) from 3rd to 2nd shell
UNIT 2 TOPIC 2 – SUBATOMIC PARTICLES & SYMBOLS
ENGAGE
Subatomic Particles & Symbols
Topic 2
He
Be
Helium
Beryllium
2 protons
4 protons
2 neutrons
electrons orbit
5 neutrons
2 electrons
protons +
neutrons in the
nucleus
4 electrons
# of protons =
# of electrons
different # of protons
from neutrons?
Subatomic Particles & Properties
Particle
Symbol
Location
Electron
e-
Outside
nucleus
Proton
p+
Neutron
n0
Electrical
Charge
Approximate
Actual Mass
Relative
(g)
Mass (amu)
1-
1/1840
(essentially 0)
9.11 x 10-28
Inside
nucleus
1+
1
1.67 x 10-24
Inside
nucleus
0
1
1.67 x 10-24
What does the unit ‘amu’ mean?
atomic mass unit (1/12 of the mass of a carbon-12 atom)
_____________________________________________
neutral
ATOMS are electrically ______________
. This means
protons must equal the
that the number of ___________
electrons .
number of ______________
Get out your Reference Tables!!
Atomic Mass
12.011
Symbol
Atomic Number
Electron Configuration
6
C
-4
+2
+4
2-4
Atomic Number: # of protons in the nucleus
Atomic Mass: # of protons + neutrons in the nucleus
We’ll get to
these later
1)
2)
3)
4)
equal numbers of each isotope are present
more isotopes have an atomic mass of 1 than of 2 or 3
isotopes have only an atomic mass of 1
more isotopes have an atomic mass of 2 or 3 than of 1
37) What is the electron configuration of a sulfur atom in the ground state?
1) 2-6
2) 2-4
3) 2-8-6
4) 2-8-4
25) What is the total number of valence electrons in an atom of electron configuration X?
38) When compared with the energy of an electron in the first shell of a carbon atom, the energy of
an electron in the second shell of a carbon atom is
1) the same
2) less
3) greater
26) What electron configuration represents the excited state of a calcium atom?
39) Which notation represents an atom of sodium with an atomic number of 11 and a mass number
of 24?
Regents Practice
2)
3)
1) atomic mass of an element
The
is the weighted average
of the masses of 4)
1) all of its radioactive isotopes
3) all of its naturally occurring isotopes
3+
40) 2)
What
the least
total number
of isotopes
electrons in a Cr ion? 4) its two most abundant isotopes
itsistwo
abundant
1) 21
2) 27
3) 24
4) 18
?
28) What is the mass number of the nuclear symbol
41) In which of the following pairs do the particles have approximately the same mass?
1)
28
2) 10
19
4) 9
1) neutron
and beta particle
3) 3)neutron
and electron
2) proton
and represents
electron
and neutron
29) Which
symbol
a particle with a total of4)10proton
electrons?
5718 42) 1)
Which
two
notations
represent
atoms
that
are
isotopes
of
the
same
element?
3+
3+
Al
2) N
3) N
4) Al
12) 1)
Which statement
is true about a proton and3)an electron?
and
andthe structure of the atom. One of
30) In the early 1900s, experiments were conducted to determine
1) They
have different
and gold
different
charges.
these
experiments
involvedmasses
bombarding
foil with
alpha particles. Most alpha particles
2) They
havethrough
different
andhowever,
the same
passed
directly
themasses
foil. Some,
were
deflected
at various angles. Based on this
2)
and
4) charges.
and
twoand
3) They
have
the same state
masses
different
charges.
alpha
particle
experiment,
conclusions
that
were made concerning the structure of an
atom.
4) They have the same masses and the same charges.
43) What is the total number of electrons in an S2- ion?
13) An atom of oxygen is in an excited state. When an electron in this atom moves from the
1) 18
2) 16
3) 14
4) 10
shell to the second shell, energy is
31)
The
modern
model of
theapproximately
atom shows that
are
44) Which
two particles
have
the electrons
same mass?
27)
47) 2)
A student measured
the wavelength of hydrogen's visible red
line to be 647 nanometers.
and
4) spectral
and
Based on the information in the reading passage, show a correct numerical setup for calculating
5718 - 1 - Page 9
the student's percent error.
Questions 83 and 84 refer to the following:
43) What is the total number of electrons in an S2- ion?
The
shows
of selected
elements.
1)
18 below
2)spectra
16 states
3) 14
4) 10
48) diagram
Explain,
in terms
of bright-line
electron energy
and energy
changes,
how hydrogen's bright-line
spectrum
is produced.
44) Which
two
particles have approximately the same mass?
1) neutron and positron
3) neutron and electron
proton
neutron present on the surface of a star can
4) beproton
andusing
electron
49) 2)
Explain
howand
the elements
identified
bright-line
Regents Practice
spectra.
45) The
atomic number of an atom is always equal to the number of its
1) protons plus electrons
3) neutrons, only
83) Explain how a bright-line spectrum is produced, in terms of excited state, energy transitions,
2)
protons plus neutrons
4) protons, only
and ground state.
50) Which ion has the same electron configuration as an atom of He?
1) O22) Ca2+
3) H -
51) Identify
What is the
the two
total
numberin
ofthe
electrons
found in spectrum.
an atom of sulfur?
84)
elements
given unknown
1) 16
2) 6
3) 32
4) Na+
4) 8
52) Which statement best describes electrons?
85) Which
diagram
represents
the nucleus
of an and
atomare
of found?in the nucleus.
1) They
are negative
subatomic
particles
2) They are positive subatomic particles and are found in the nucleus.
3) They are negative subatomic particles and are found surrounding the nucleus.
1)
2)
4)
4) They are positive subatomic
particles and are3)
found surrounding the nucleus.
53) In the box below, draw a Lewis electron-dot diagram for a sulfur atom in the ground state.
86)
In the box below, draw a Lewis electron-dot structure for an atom of phosphorus.
Look at the following sample of 100 Neon atoms in the “Jazz” sign. How many
different types of Neon atoms are there in the sample? What is different about them?
Which type is most abundant? Which type is least abundant?
Isotopes
Find Neon on the Periodic table and look at its Atomic Mass. What connection can
Topic 3
you make between Neon’s Atomic Mass and this sample of atoms?
Notation of Atoms
35Cl
Cl-35
Chlorine-35
Chlorine - 35
Chlorine - 37
17 p
18N
17 p
20N
Isotopes (Iso-, meaning same)
Atoms with same # of protons, different # of neutrons
What are three things that are the same between
atoms that are isotopes?
1. Same chemical properties
2. Same atomic number
3. Same number of electrons
What are two things that are different?
1. Different number of neutrons
2. Different mass numbers
otopes = ___________________________________________________________
… What are three things that are the same between atoms that are isotopes?
1.
Remember!
2.
3.
What are two things that are different?
1.
Number of protons
2.
defines the element.
emember!!!
Number
of neutrons
1. The number
of protons
defines the element.
determines the isotope
2. The number of neutrons determines which
isotope of a given element you have.
However, their atomic masses are not the same because the number of
neutrons of the atomic nucleus of each isotope varies. In the case of
helium, both isotopes have two protons in their nuclei. However, helium-3
has one neutron, while helium-4 has two neutrons.
Table 4 lists the four stable isotopes of lead. The least abundant of
these isotopes is lead-204, while the most common is lead-208. Why do all
lead atoms have 82 protons and 82 electrons?
www.scilinks.org
Topic : Atoms and Elements
SciLinks code: HW4017
Lead’s Isotopes
Table 4
The Stable Isotopes of Lead
Name of atom
Symbol
Number of neutrons
Mass number
Mass (kg)
Abundance (%)
Lead-204
204
82Pb
122
204
203.973
1.4
Lead-206
206
82Pb
124
206
205.974
24.1
Lead-207
207
82Pb
125
207
206.976
22.1
Lead-208
208
82Pb
126
208
207.977
52.4
Chapter 3
Atomic Mass: given to a number of decimal places. This is because,
in most cases, there are a number of naturally occurring isotopes.
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Mass Number: the number of protons and neutrons in the isotope.
2. Look at a Periodic Table....Atomic mass is given to a number of decimal places.
This is because, in most cases, there are a number of naturally occurring
isotopes. Mass vs. Mass Number
Atomic
Isotope
Hydrogen-1
Hydrogen-2
(deuterium)
Hydrogen-3
(tritium)
Atomic Number of Number of Number of
Number Protons
Neutrons Electrons
Mass Number
(amu)
1
1
0
1
1
1
1
1
1
2
1
1
2
1
3
Hydrogen
three
isotopes.
= 1.0079 amu)
Hydrogen
has threehas
isotopes,
each
with a whole(Atomic
number formass
a mass number.
Yet, hydrogen as an element has an atomic mass on the periodic table of1.0079
1.0079 amu.
Based
this information,
Which
isotope on
of hydrogen
must be the mostwhich
abundant, based on this data? ____
isotope must be the most abundant?
H
Write it in correct notation.____________________________________________
1
For example:
Hydrogen has three isotopes, each with a whole number for a mass number.
Yet, hydrogen as an element has an atomic mass on the periodic table of 1.0079 amu.
Which isotope of hydrogen must be the most abundant, based on this data? ____
WriteExample
it in correct notation.____________________________________________
For example:
A natural sample of C (atomic mass = 12.011 amu) is a mixture of C-12 (98.89%) and
C-14 (1.11%).
6 has an average atomic mass of __________
12.011 amu,
Carbon's atomic number is ______,
12 amu.
and carbon's most common isotope has a mass number of ______
6 protons, ______
6
Therefore, the most common type of carbon atom has _______
6 electrons. Another naturally-occurring isotope of carbon is Cneutrons and ______
14, but it is rare in comparison to the amount of C-12 in nature.
13)
An
atom
of oxygen
is best
in an
excitedanstate.
6)
Which
of these
phrases
describes
atom?When an electron in this atom moves from the thir
best
6) shell
Which
these
phrases
describes
an atom? embedded
toofthe
second
energy
is uniformly
1)
a hard
sphere
withshell,
positive
particles
1) aaabsorbed
hardsphere
sphere
with
positive
particles
uniformly
embedded
2)
hard
negative
particles
uniformly
embedded
by with
the
electron
3) emitted by the electron
2) aaemitted
hard sphere
negativeby
particles
uniformly
embedded
3)
positive
nucleus
surrounded
a cloud of
negative charges
2)
by
thewith
nucleus
4) absorbed by the nucleus
4)
surrounded
by aby
hard
negative
shell
3) aapositive
positivenucleus
nucleus
surrounded
a cloud
of negative
charges
5718
- 1 - Page
14) What is the total number of valence electrons in an atom of sulfur in the ground
state?
4) a positive
surrounded
by aofhard
negative
shellin an atom
7) Which
According
to thenucleus
wave-mechanical
model
the
atom,
electrons
24)
radioisotope
is
used
in
medicine
to
treat
thyroid
disorders?
1)
6
2)
8
3)
3
4) 4
1) have a positive charge
7)
Regents Practice
According
to the wave-mechanical model of the atom,
in an atom
1)
uranium-238
3)electrons
cobalt-60
2) the
are box
located
in orbitals
outside
nucleus
15) In
below,
draw
a Lewisthe
electron-dot
diagram of a selenium atom in the ground state
1)
have
a
positive
charge
2)
iodine-131
4) phosphorus-32
3) are most likely found in an excited state
2) are located in orbitals outside the nucleus
Questions
25 and
26 refer
to the following:
4) travel
in defined
circles
3) are most likely found in an excited state
8)
What is the total number of neutrons in the nucleus of a neutral atom that has 19 electrons and a
4) travel in defined circles
8)
9)
mass number of 39?
What
neutrons in the nucleus
has 19 electrons and a
1)
19 is the total number
2) of20
3) 58of a neutral atom that
4) 39
mass number of 39?
What is the mass number of an atom that has six protons, six electrons, and eight neutrons?
1) 19
2) 20
3) 58
4) 39
1) 6
2) 20
3) 14
4) 12
9)
What is the
number
of an atom
10) Compared
to mass
a proton,
an electron
has that has six protons, six electrons, and eight neutrons?
1) the
6 issame
2)
20 the electrons
14of electron configuration
4) 12X?
25) What
the total
number
of valence
in an3)
atom
1)
quantity
of charge
and
opposite sign
16)
electrons
contained
in ansign
Au3+ ion?
2)
themany
sameto
quantity
ofare
charge
and the
same
10) How
Compared
a proton,
an electron
has
3) a82
greater quantity of charge
the same sign
1)
2) and
197
1) the same quantity of charge
and the opposite sign 3) 76
26)
17)
4) a greater quantity of charge and the opposite sign
4) 79
What
electron
configuration
the
of a calcium atom?
14
2) the
quantity
of charge
and thein
same
sign ofstate
What
issame
the total
number
of represents
neutrons
anexcited
atom
aluminum-27?
11) Which electron configuration represents an atom of chlorine in an excited state?
3) a greater quantity of charge and the same sign
1)
2-8-8 and the opposite
3) sign
2-8-7
4) 2-8-6-1
4) 2-8-7-1
a greater quantity of2)charge
27)
atomic
massconfiguration
an element
is the weighted
average
of theinmasses
of state?
11) The
Which
electron
represents
an atom
of chlorine
anan
excited
18)
Compared
to
an of
electron
in the
first electron
shell
of an
atom,
electron
in the third shell
1)
of its
radioactive
isotopes
3) 2-8-7
all of its naturally occurring
isotopes
1) all
2-8-7-1
2) 2-8-8
3)
4) 2-8-6-1
the
same
atom
has
2) its two least abundant isotopes
4) its two most abundant isotopes
28)
1) less energy
2) more mass
What is the mass number of the nuclear symbol
?
3) less mass
4) more ener
19) In the modern wave-mechanical model of the atom, the orbitals are regions of the most prob
Topic 3 - Review
Isotopes: Same protons, different neutrons
Mass Number: # of protons and neutrons in an
isotope
Atomic Mass: Given in decimal form, showing that
more than one isotope can be present
Bohr & Lewis Dot Structures for Electrons in
Atoms