Download Unit 3: Chemistry. Introduction to Atoms. Atomic mass

Bell Ringer
THINK BACK TO LAST CLASS & The History of the Atom! WITHOUT using your notes match the scientist to
the correct statement that describes his work.
Ernest Rutherford
John Dalton
J.J. Thomson
Democritus
Schrodinger & Heisenberg
Niels Bohr
1. _______________________________ proposed that all matter is made up of tiny particles called atoms
(from the word that means "indivisible.")
2. _______________________________ suggested that electrons travel in well-defined paths.
3. _______________________________ discovered that atoms have electrons and thought that they were
embedded in positively charged material.
4. _______________________________ proposed that matter is composed of atoms and the atoms of an
element are identical. His Atomic Theory suggested that atoms can be thought of as being much like a small
uniformly solid ball.
5. _______________________________ concluded that there is a small, dense, positively charged nucleus.
6. ______________________________ proposed that electrons travel in electron clouds.
Unit 3: Chemistry. Introduction to Atoms.
How big is an atom?
On average the
diameter is
0.00000003 cm!
Unit 3: Chemistry. Introduction to Atoms.
LET’S WATCH THE TED ED VIDEO!
https://www.youtube.com/watch?v=yQP4UJhNn0I
Unit 3: Chemistry. Introduction to Atoms.
What is inside an atom?
Electrons: are negatively
charged particles found
in electron clouds
outside the nucleus.
Protons: are positively
charged particles in the
nucleus if the atom.
Neutrons: are
particles in the
nucleus of an
atom that have no
charge.
The Nucleus: is the
small, dense,
positively charged
center of the atom. It
contains most of the
atom’s mass.
The diameter of the nucleus
is 1/100,000 the diameter of
the atom.
Unit 3: Chemistry. Introduction to Atoms.
Atomic mass unit (amu): the SI unit used
to express the masses of particles in
atoms
Proton
Neutron
Electron
Charge: positive
Charge: none
Charge: negative
Mass: 1 amu
Mass: 1 amu
Mass: almost zero
Location: nucleus
Location: nucleus
Location: electron clouds
Unit 3: Chemistry. Introduction to Atoms.
Fun Fact: If it were possible to have a nucleus
the volume of an average grape, that nucleus
would have a mass greater than
9 MILLION TONS!
Unit 3: Chemistry. Introduction to Atoms.
The atom is neutral when
there are equal number
protons and electrons.
If the number of protons
and electrons are not
equal, the atoms
becomes a charged
particle called an ion.
Unit 3: Chemistry. Introduction to Atoms.
Stop and think…
1)What particles form the
nucleus?
2)Explain why atoms are
neutral.
Unit 3: Chemistry. Introduction to Atoms.
Atomic number: the number
of protons in the nucleus.
This # determines what type
of element it is!
Atomic mass: the sum of the
protons and neutrons in an
atom
Unit 3: Chemistry. Introduction to Atoms.
Isotopes are
atoms that have
the same number
of protons but
have different
number of
neutrons.
Unit 3: Chemistry. Introduction to Atoms.
Calculate the number of neutrons for
these carbon isotopes!!!
_____ neutrons
_____ neutrons
Atomic Mass
-Number of protons
Number of neutrons
_____ neutrons