1. Chapter 11
Introduction to Atoms

2. The History of Atomic Theory
___________________ proposed that all atoms are _________, __________
particles made up of a single material formed into different _____________
and ____________. He also said that that atoms are always _____________
and can form different _________________ by ______________ together.
Democritus
small hard
shapes
sizes
moving
materials
joining
In the 1700s, ________ ____________ came up with an atomic theory with
3 parts: 1. All substances are made of __________ which are
small particles that cannot be ____________, _____________,
or ___________________.
2. Atoms of the same ________________ are exactly alike
and atoms of different _______________ are ______________.
3. Atoms __________ with other atoms to make new
___________________.
John Dalton
atoms
created divided
destroyed
element
element
different
join
substances
3. In 1897, ______________________discovered that there
are small particles _______________ the atom. He found
that these particles had a _________________ charge. He
called the particles ___________________, now known as
_______________. He came up with a model of the atom
known as the ___________________ model, where the atom
is mostly ______________ charged material with ________________located
throughout, so that the entire atom would be neutral in charge.
J.J. Thomson
inside
negative
corpuscles
electrons
plum-pudding
positively
electrons

3. Ernest Rutherford
4. In 1909, ________________________ aimed a beam of ____________
particles at some gold foil and found that most of the particles ____________
_______________ the foil, some were ______________ a little, and a few
bounced straight back. He concluded that atoms have a small, dense, positively
charged _______________ in the center with ______________ orbiting around
it, and that atoms are mostly _____________ ______________.
alpha
went
through
deflected
nucleus
electrons
empty space
5. In 1913, __________________ came up with a model
of the atom where the _______________ travel in definite
______________ around the nucleus. These
_______________ can jump from one _____________
to the next, but cannot stay _________________
the levels.
Neils Bohr
electrons
paths
level
electrons
between

4. The work of ____________________ and
____________________ contributed to the
modern atomic theory, which says that the
exact path of a moving electron cannot be
_______________. There are
_______________ where the electron
is likely to be called _______________ ____________.
Erwin Schrodinger
Werner Heisenberg
predicted
regions
electron clouds
Atoms consist of 3 _______________ _______________:
1. Protons: ________________ charged particles in the ____________
of the atom. Their mass is equal to 1 AMU (__________ _______ _____).
An AMU = __________________ g.
2. Neutrons: _________________ particles in the _____________ of the
atom. Their mass is _________________.
3. Electrons: ________________ charged particles within the _________
_____________ of an atom (outside the ______________). Their mass
is about _________ AMU and is usually considered to be ___________.
subatomic particles
positively
nucleus
atomic mass unit
1.7 x 10-24
uncharged
nucleus
1 AMU
negatively
electron
cloud
nucleus
1/1800
zero
The _____________ of an atom is ______________. Atoms can __________
1 or more electrons and become _________________ charged _________ or
_____________ 1 or more electrons and become ______________ charged
__________. A neutral atom has equal numbers of ____________ and _________.
charge
zero
lose
positively
ions
gain
negatively
ions
protons electrons

5. Elements: All atoms of a particular element have the same number of
___________ in their nuclei. The number of protons is the ___________
_____________ of the element or atom. Neutral atoms will have the same
number of _______________. For example, all atoms of hydrogen have ___
proton in the nucleus. All atoms of helium have ____ protons in the nucleus.
All atoms of carbon have ____ protons in the nucleus.
protons
atomic
number
electrons 1 2 6
Different atoms of the same element may have different masses. This is
because they can have different numbers of ______________ in the nucleus.
For example, an atom of hydrogen can have one ____________ and _______
neutrons in its nucleus, or one _____________ and ______ neutron, or one
____________ and _______ neutrons. These atoms of the same element with
different masses are called ______________.
neutrons
proton
zero
proton
one
proton
two
isotopes

6. Isotopes: atoms that have the __________ number of ____________ but
different numbers of _______________. Some isotopes of an element may
be ______________ while others may be _________________. All isotopes
of a particular element have the same _______________ and ______________
properties.
same
protons
neutrons
stable
radioactive
chemical physical
Mass Number: This is equal to the sum of the ____________ plus the
______________ of an atom. The mass of the ____________ is not included
because it is so _____________. The number for an element’s mass listed on
the periodic table is a weighted ________________ of all the naturally occurring
_______________ of a particular _________________.
protons
neutrons
electrons
small
average
isotopes
element
Example: An atom has 6 protons,
8 neutrons, and 6 electrons. What is the
a. atomic number? ______
b. mass number? ______
c. element? _______________
Example: If an atom of sulfur has a mass
number of 34, how many neutrons
does the atom have? ______ 6 14
carbon 18

7. Calculating Atomic Mass: Multiply the mass number of each _______________
by its __________________ and add them all together.
Example: The percentages for the isotopes of copper are
69% Cu-63 and 31% Cu-65. What is the atomic mass of Copper?
____________________________________________
isotope
percentage
.69 x 63 = amu
.31 x 65 = amu
= amu
Example: The 5 isotopes of titanium are:
Ti-46 (8.0%) ______________________
Ti-47 (7.3%) ______________________
Ti-48 (73.8%) ______________________
Ti-49 (5.5%) ______________________
Ti-50 (5.4%) ______________________
Total: ____________________
46 x 0.08 = 3.68 amu
47 x .073 = amu
48 x .738 = amu
49 x .055 = amu
50 x .054 = 2.7 amu
47.93 amu
Forces acting in Atoms
1. Gravity – This depends on the _________ and ____________ between 2
objects. Since atoms are so _____________, this force is very
____________ in atoms.
mass
distance
small
weak

8. 2. Electromagnetic Force – Objects with the same charge __________
each other while objects with opposite charges _____________
each other. ____________ and ______________ are attracted
to each other because they have _______________ charges.
The ________________________ force holds the electrons
around the protons.
repel
attract
Protons
electrons
opposite
electromagnetic
3. Strong Force – At the close distances between __________ in the
nucleus, the ____________ force holds them together and
is stronger than the ______________________ force that
would cause them to fly apart.
protons
strong
electromagnetic
4. Weak Force – This force plays a role in ___________________
atoms where a ______________ can change into a
_____________ and an _______________.
radioactive
neutron
proton
electron

9. Chapter 11
Introduction to Atoms

10. The History of Atomic Theory
___________________ proposed that all atoms are _________, __________
particles made up of a single material formed into different _____________
and ____________. He also said that that atoms are always _____________
and can form different _________________ by ______________ together.
moving
In the 1700s, ________ ____________ came up with an atomic theory with
3 parts: 1. All substances are made of __________ which are
small particles that cannot be ____________, _____________,
or ___________________.
2. Atoms of the same ________________ are exactly alike
and atoms of different _______________ are ______________.
3. Atoms __________ with other atoms to make new
___________________.
3. In 1897, ______________________discovered that there
are small particles _______________ the atom. He found
that these particles had a _________________ charge. He
called the particles ___________________, now known as
_______________. He came up with a model of the atom
known as the ___________________ model, where the atom
is mostly ______________ charged material with ________________located
throughout, so that the entire atom would be neutral in charge.

11. 4. In 1909, ________________________ aimed a beam of ____________
particles at some gold foil and found that most of the particles ____________
_______________ the foil, some were ______________ a little, and a few
bounced straight back. He concluded that atoms have a small, dense, positively
charged _______________ in the center with ______________ orbiting around
it, and that atoms are mostly _____________ ______________.
5. In 1913, __________________ came up with a model
of the atom where the _______________ travel in definite
______________ around the nucleus. These
_______________ can jump from one _____________
to the next, but cannot stay _________________
the levels.

12. The work of ____________________ and
____________________ contributed to the
modern atomic theory, which says that the
exact path of a moving electron cannot be
_______________. There are
_______________ where the electron
is likely to be called _______________ ____________.
Atoms consist of 3 _______________ _______________:
1. Protons: ________________ charged particles in the ____________
of the atom. Their mass is equal to 1 AMU (__________ _______ _____).
An AMU = __________________ g.
2. Neutrons: _________________ particles in the _____________ of the
atom. Their mass is _________________.
3. Electrons: ________________ charged particles within the _________
_____________ of an atom (outside the ______________). Their mass
is about _________ AMU and is usually considered to be ___________.
The _____________ of an atom is ______________. Atoms can __________
1 or more electrons and become _________________ charged _________ or
_____________ 1 or more electrons and become ______________ charged
__________. A neutral atom has equal numbers of ____________ and _________.

13. Elements: All atoms of a particular element have the same number of
___________ in their nuclei. The number of protons is the ___________
_____________ of the element or atom. Neutral atoms will have the same
number of _______________. For example, all atoms of hydrogen have ___
proton in the nucleus. All atoms of helium have ____ protons in the nucleus.
All atoms of carbon have ____ protons in the nucleus.
Different atoms of the same element may have different masses. This is
because they can have different numbers of ______________ in the nucleus.
For example, an atom of hydrogen can have one ____________ and _______
neutrons in its nucleus, or one _____________ and ______ neutron, or one
____________ and _______ neutrons. These atoms of the same element with
different masses are called ______________.

14. Isotopes: atoms that have the __________ number of ____________ but
different numbers of _______________. Some isotopes of an element may
be ______________ while others may be _________________. All isotopes
of a particular element have the same _______________ and ______________
properties.
Mass Number: This is equal to the sum of the ____________ plus the
______________ of an atom. The mass of the ____________ is not included
because it is so _____________. The number for an element’s mass listed on
the periodic table is a weighted ________________ of all the naturally occurring
_______________ of a particular _________________.
Example: An atom has 6 protons,
8 neutrons, and 6 electrons. What is the
a. atomic number? ______
b. mass number? ______
c. element? _______________
Example: If an atom of sulfur has a mass
number of 34, how many neutrons
does the atom have? ______

15. Calculating Atomic Mass: Multiply the mass number of each _______________
by its __________________ and add them all together.
Example: The percentages for the isotopes of copper are
69% Cu-63 and 31% Cu-65. What is the atomic mass of Copper?
____________________________________________
Example: The 5 isotopes of titanium are:
Ti-46 (8.0%) ______________________
Ti-47 (7.3%) ______________________
Ti-48 (73.8%) ______________________
Ti-49 (5.5%) ______________________
Ti-50 (5.4%) ______________________
Total: ____________________
Forces acting in Atoms
1. Gravity – This depends on the _________ and ____________ between 2
objects. Since atoms are so _____________, this force is very
____________ in atoms.

16. 2. Electromagnetic Force – Objects with the same charge __________
each other while objects with opposite charges _____________
each other. ____________ and ______________ are attracted
to each other because they have _______________ charges.
The ________________________ force holds the electrons
around the protons.
3. Strong Force – At the close distances between __________ in the
nucleus, the ____________ force holds them together and
is stronger than the ______________________ force that
would cause them to fly apart.
4. Weak Force – This force plays a role in ___________________
atoms where a ______________ can change into a
_____________ and an _______________.