Download Name: Per: ______ Atoms: The Building Blocks of Matter Atoms

Name: ___________________________ Per: ________
Atoms: The Building Blocks of Matter
Atoms, Molecules and Compounds
•Atoms:
Dalton’s Atomic Theory
1.All matter is made of _________________.
2.Atoms of one element differ in___________________ (size, mass
etc…) from atoms of another element.
3.Atoms of different elements combine in simple,
________________________ ratios to form molecules.
4.In chemical reactions atoms can combine, ______________________
and rearrange, but not destroyed.
Structure of the Atom
Atoms consist of two regions:
1.Nucleus: Which is a very ____________region located in the center of an atom which contain
positively (+) charged particles called ____________________ and one or more (=) neutral particles
called _____________________.
2.Electron cloud: A region very _______________ compared to the nucleus which contains very small
negatively (-) charged particles called ___________________________.

Neutrons, protons and electrons are called _________________
______________________.

_________________________ are much smaller in size and mass than
neutrons and protons.
Discovery of the Electron

______________________ ______________ experiments performed by
JJ Thompson provided evidence that ___________ atoms
contained negatively charged particles.
Questions Raised by the Discovery of the Electron

If it is true that all atoms have these super tiny negatively charged particles two main
questions arise:
1. Because atoms are electrically _________________, they must contain a positive charge to
balance out negative __________________.
Name: ___________________________ Per: ________
2. Because electrons have so much __________ mass than atoms, atoms must contain other
_____________________ that account for most of their mass.
Discovery of the Atomic Nucleus

Rutherford discovered that all atoms have a very small,
_________________ and positively charged nucleus by
performing what we call the “_____________ foil
experiment.”
Rutherford’s Conclusions

Most of the _________ and all of the ______________ charge
of the atom is in a very dense nucleus.

However the nucleus only takes up a very
_______________ space in an atom.

Atoms are mostly _____________ _____________.
EXAMPLE: If the nucleus of an atom was the size of a _____________, the size of the ____________ would
be equal to a football field.
The Charges:
Proton: +1;
mass = 1 amu
Neutron: 0 charge; mass = 1amu
Electron: -1;
mass = .00055 amu (almost nothing)
Atomic Number

Atomic Number: (Z) tells you how many __________________ are in each atom of an
_________________. The atomic # _____________________ the element.

Chemical Symbol: Is the _______________ abbreviation for an __________________.
Label the atomic # and chemical symbol:
Name: ___________________________ Per: ________
List how many protons are in the following
Element:
Protons:
Element:
Protons:
Element:
Protons:
Isotopes

Isotopes: are atoms of the _____________ element that have different _________________.

Isotopes of a particular element all have the same number of _________________ and
__________________, but different numbers of _____________________.
Reading the Periodic Table
Mass Number
•Mass Number: (A) is the total number of ________________ and ______________ that make up the nucleus
of an isotope.
•Mass Number (A) – Atomic Number (Z) = Number of Neutrons
Mass Number can be written two ways:
How many protons, electrons & neutrons are in Carbon 14?
Protons: Always _________ in carbon
Electrons: Same as protons, or __________
Neutrons = Mass# - protons
Neutrons: ______________ = 8 neutrons
Average Atomic Mass
•Although ______________________ have different masses, they do not differ significantly in their
_______________________ behavior.
Name: ___________________________ Per: ________
•Average atomic mass: the _____________________ average of the atomic masses of the naturally
occurring isotopes of an _______________________.
•Basically two things matter: the ____________ and ________________ abundance of an elements isotopes.
Example:
A sample of nitrogen has some different isotopes in it. According to a mass spectrometer
experiment, the following data is obtained:
99.64% atoms are N 14 _________________
0.36% atoms are N 15 isotopes
The weighted ________________ is 14.0067
This is the value you find on the
______________________.
Life is a little more complicated…
•Compound:
•Molecule
•Ion:
Please use the space below to write 3-4 sentences summarizing your notes: