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Chemistry 11 – Early models of the atom
1
Structure of the Atom
Democritus
• Developed the idea of ___________
• Thought “things” were made of atoms that have
different ___________
Aristotle
• Matter is made of different amounts of:
___________,___________,___________,
and___________
John Dalton
•
ompnd
•
JJ Thomson
•
Elements are made up of very
______________________ atoms.
An element is made up of a group of
___________atoms.
A particular combination of specific types of
atoms creates ______________________.
Chemical reactions involve the re-shuffling of
the atoms in a compound to make new
compounds.
Atoms contain ___________.
•
______________________________________
•
atoms
•
.
e-
______________________________________
______________________________________
__________________.
Plum
pudding
•
“______________________” Model (Draw in
the box)
model
e
-
e
e
'
e
-
-
Chemistry 11 – Atomic Theory Study Guide
1
Subatomic Particles: Electrons, Protons, and Neutrons
For
Rutherford-Bohr Model:
He
neutral
•
•
+
,
t
electron
-
+
2
>
U
neutron
pt
2
,
-
e
)
proton A )
}
#
Pt
nucleus
¥32
etts
Atomic
#
=
2
=
Ptt
#
n
4
#
Definitions:
Positively charged subatomic particle found in nucleus.
• Proton: ______________________________________________________________________
subatomic particle found in nucleus.
• Neutron:Neutral
_____________________________________________________________________
• Electron:Negatively
_____________________________________________________________________
charged very light subatomic particle.
Mass
Electron
Symbol
Charge
Mass (amu)
=
=
#
Proton
pt
e-
Neutron
n
+
-
0
1
lightest
but
Atomic Number and Mass Number
Look at K for example:
Atomic
Number
_________________
Atomic
Mass
_________________
↳
=
#
# Ptt
#
Different
up
most
space
_________________
Symbol
pt
#
takes
19
K
Potassium
39.098
_________________
Name
n
from
Mass
#
#
=
Ptt
#
n
Definition:
Atomic Number:
# of p+ in the nucleus
Of an element is the _______________________________________________
of its atoms.
No two elements have the _______
Same atomic number.
This number defines an ________________.
Element
Increases by ______
as
you
go through the periodic table (refer to periodic table)
One
.
•
Number of protons = _________________________________
# of e-
(in neutral atoms)
Therefore, for K: 19 protons = ______
19 electrons in a neutral atom.
Chemistry 11 – Atomic Theory Study Guide
2
So how do we fill the electrons in the shells?
•
We follow the rule that certain shells can hold a certain number of electrons.
2
1st shell: ___ e8 e2nd shell: ___
3rd shell: ___
8 e
th
4 shell: ____
18 e …etc. We will only focus on the first 20 elements for now!
Bohr Diagram for K:
.
.
K
neutral
.
÷.
:
atomic
lqpt
.
.
i.
#
=
19
=
#
pt
#
e-
=
Ions:
Energy
Removed from an atom if enough ____________
• Electrons can be ______________
is applied to it.
For example,
•
•
Na atom
sodium atom
11 protons
11 electrons
Na+
sodium ion
11 protons
10 electrons
→
remove e-
Full and stable outermost (valence) shell.
Ions usually form as a result of atoms having _________________________________________.
+ve charged ions have ______
electrons
Gained
Lost electrons, while –ve charged ions have __________
Leaton
Bohr Diagram for Na+:
.
.
:
.
llpt
.
.
-
For
.
l
anion
Nat
atomic
#
11
=
#
=
# e-
pt
1=10
=11
How do we find out the number of neutrons in an atom?
the
on
not
appear
Integer ( Does
Definition:
ctable )
Mass number:
p
= Sum of # of p+ and n in the nucleus.
__________________________________________________________________.
-
Can increase by more than one when going from
__________________________________________________________________.
one element to the next one.
Chemistry 11 – Atomic Theory Study Guide
•
By convention,
Mass number
________
Atomic number
_________
=
=
.fr#ic
#
Of
pttn
#
↳
Example using K:
3
39
Pt
-
19K
Different
#
n
=
taYwa#ys5
greater
mass
20
How many neutrons are present in an atom of K that has mass number = 39?
mass number = number of protons + number of neutrons
number of neutrons = Mass # - #p+
=
39
19
=
20
-
Isotopes
•
Neutron (remember
Not all atoms of the same element contain the same number of ___________
number of protons determines the identity of elements, NOT the number of neutrons).
Definition:
Isotopes:
Atoms of the same element having different mass (or different # of n)
_______________________________________________________________________
Example: Carbon, C has three naturally occurring isotopes: C-12, C-13,
oooC-14
Mass
#
Summary:
When #p+
is changed
= form different element
Electron
Configuration
When #e- is changed = form ion (anion or cation)
When #n is changed = form isotope
Definition:
Electron Configuration:
• _______________________________________________________________________
_______________________________________________________________________
4 types of shells:
• s orbitals can hold ___ e• p orbitals can hold ___ e• d orbitals can hold ___ e• f orbitals can hold ___ e-
Chemistry 11 – Isotope Calculation Study Guide
!
Isotope Calculation
Complete the following table:
!"
!!
!"
!!
or C-12
# of p+
6
or C-13
!"
!!
6
6
66
12
13
-
# of e
6
6
12-6-6
# of n
+
Atomic # (# of p )
+
Mass # (# p + n)
13-6=7
6
Atomic mass
rltrom
or C-14
14-6=8
6
14
tabTe2°0
periodic
Why is the mass number of element different from the atomic mass?
The mass number is a whole number which represents sum of # of p+ and n but atomic mass is usually a
decimal number which represents the molar mass of the element.
same
as
atomic
Has a unit
- g/mol
mass
Definition: Weighted average of masses of all isotopes of an element.
Molar mass: ________________________________________________________________________
e.g., Molar mass of Cl is ____________.
35.591mA Where did this number come from?
• Scientific data tells us that there are two isotopes of chlorine Cl-35 and Cl-37. 75.77% of the element is
Cl-35 and 24.23% of it is Cl-37.
fsigma
!"#$%!!!"##! = !
=
take
sum
=
find
total
!"#$%&'(!!"!!"#$#%& !!!(!"##!#!)
75.77400-350%-1.230104037
0.7577×351+(0.2423×37)=35.4814161
=( MMC d)
35.51¥
=
e.g., What is the molar mass of boron, given that there are:
• 18.8% of B-10
MMCB
• Rest is all B-11
188×10
)=(.
)t(.812×11 )
µ
100010-18.8010
=
10.81$
=
81.2010
e.g., What is the molar mass of magnesium, given that there are:
• 78.99% of Mg-24
=
• 10.00% of Mg-25 MMC
Mg )
• Rest is all Mg-26
!
H
=
(1101×26)
+
(7899×24)+(1000×25)
-24,3M¥
=
!
10.81€
100010-78.99010-10.0040=11.01010
24.32/0/21
Quiz
Atomic Theory
Quiz 1 Review
includes
Molar
calculation
mass
-→ ffaxsts
1. Complete the following table to summarize properties of subatomic particles.
Subatomic
Location
Relative mass
Charge
particle
Nucleus
proton
1836
+1
Nucleus
neutron
1837
Neutral
Electron cloud
electron
1
-1
2. Summarize the contribution of each scientist on atomic theory
Scientists
Contribution
John Dalton
Defined how an element is made up of a same type of particles known as
atoms. Compound is made up of multiple types of atoms.
JJ Thomson
Contributed to the discovery of electrons and developed plum pudding
model.
Ernest Rutherford
Through gold foil experiment, discovered the presence of concentrated
positive charge in the core of an atom. (Proton and nucleus)
Electrons circulate around the nucleus of an atom within a specific electron
shell.
Niels Bohr
Erwin Schrodinger
Electrons are found within electron clouds but their exact location can
never be known.
3. Complete the following table. The first two rows are completed as examples.
Isotope
Protons
Neutrons
Electrons
Mass #
Charge
6
6
6
12
Neutral
17
18
18
35
-1
86
222
Neutral
14
10
27
+3
74
54
!"
!C
[ !"
!"Cl ]
28262
[ Efste ]
800 ]
'
22286
86
Rn
[ BAD
[
"
'→
27-14
=
-2
'
!"
!"Mo
[ jEHs]⇒
Y
=
13
52
136
52+1,426
8
16-8=8
10
16
42
96-42=54
42
96
108
26=5
,Tf°g
105
265
-2
-2
Neutral
+3
Atomic number = # of protons
Mass # = # of p + # of n (Mass # is different from atomic mass. Atomic mass is the average mass of all isotopes.)
Number of e depends on the charge of the isotope.
# p = # e for neutral isotopes.
# p > # e for cations.
# p < # e for anions.
!
Chemistry 11 – Atomic Theory Study Guide
Electron Configuration Introduction Inquiry Activity
Column
Element
-
#e
Row
Block
Number
within the
,
letter
,
superscript
Electron configuration
block
1s22s1
Li
3
2
S
1
Be
4
2
S
2
1s22s2
N
7
2
1s22s22p3
F
9
2
p
3
P
15
3
Mn
25
Br
35
4
P
3
Y
39
P
*
4
p
*
5
1s22s22p5
5
d
1s22s22p63s23p3
1s22s22p63s23p64s23d5
5
1s22s22p63s23p64s23d104p5
5
d
1s22s22p63s23p64s23d104p65s24d1
1
Questions:
Z superscript
1. How is the # of e- for an element related to the number found in its electron configuration?
=
#
-
e
2. How is the location of the element (row) related to the number found in its electron
Row
Row
# s
final
in
number
3. How is the location of the element (block) related to the number found in its electron
configuration?
=
configuration?
=
Block
final letter
4. How is the location of the element (column) related to the number found in its electron
=
final
superscript
5. The numbers in front of letters represent ________________________.
row
configuration?
Column
=
6. The letters represent ________________________.
block
-
7. The superscripts represent ________________________.
# e
←
ROW
->
→
1522522136352 3p6 452
552-449
→
→
1
23
4
5
I
67
}d'04p6
-
8
=3
9
10
-7
→
column
I
e-
configuration