Atoms
Molecules
Elements
All matter is made up of particles
(atoms and molecules)
Atoms
No,
not
The
Atoms
Family!
These Atoms
Atoms:
The smallest particles of matter that can not be divided into
smaller parts without changing their properties
Parts
of
an
Atom
Parts of an Atom
•Nucleus – Center of an atom
made up of protons and neutrons
•Proton – Subatomic particle with a positive charge
•Neutron – Subatomic particle with no charge
•Electron – Subatomic particle with a negative charge
Protons and neutrons have a much larger
mass than an electron.
Protons and neutrons are about
2000 times the mass
of an electron
Proton/Neutron
But…
They both have equally
strong charges!
Hi there little
guy!
Who are you calling
little? I’m just as
strong as you!
Electron
Electrons circle the nucleus in a fixed distance
Orbits - The path in which electrons move
Part of what holds an atom together is the attraction between
the positive protons and the negative electrons
Proton
Electron
or….
+
-
Hi there little
guy!
Who are you calling
little? I’m just as
strong as you!
Man, those
electrons sure
are negative!
Elements
Elements
Substances
made up of
only one kind of
atom.
Cats are not
elements!
Elements
Substance made up on only one kind of atom
Gold is an example
There are more than 100 elements
Most elements are solid at room temperature
Only a few are gas or liquid at room temperature
Molecule
Molecules
are made up of 2 or
more atoms joined
together.
A molecule
is the
smallest
bit of a
substance.
Many elements
occur as molecules, not just 1 atom.
Most elements are metals and are
solid at room temperature
Mercury and bromine are the only
metals that are liquid
at room temperature
A thermometer
Is an example
of liquid
mercury
Metals have familiar properties:
Malleable – can be hammered into thin sheets
Ductile – can be formed into wires
Conduct - can transfer electricity
Alloys are mixtures of metal such as bronze or steel
Insulators – conduct little or no electricity
Each element has an atomic number
For example:
Hydrogen has only 1 proton in its nucleus
So it has an atomic number of 1
Oxygen has 8 protons in its nucleus
So it has an atomic number of 8
Let’s look at the Periodic Table to check out atomic numbers
No, not that
table!
Periodic Table
Grouping of elements by similar properties
Arranged by atomic number
Invented in 1869 by Dmitri Mendeleev, a Russian chemist
•Each column of elements are a part of a group
(they often have same number of electrons in the outer energy levels of their atoms)
•Elements on the left side are metals (except for hydrogen)
•Elements on the far right are non-metals
•Elements with properties of both metals & nonmetals are metalloids
•Every element in the table is shown as an abbreviation known as the chemical symbol
Compounds – substance formed when the atoms of
2 or more elements combine.
When atoms join to form a compound, they go through a
chemical change (the properties of the compound are
different from the properties of the elements in it).
Water is an example of a Compound
H20
Chemical Formula
Shows which elements and how many atoms of each are in a compound.
Water
H2O
2 hydrogen atoms
join
1 oxygen atom
Salt
NaCl
1 sodium atom
joins
1 chlorine atom
Sugar (glucose)
C6H12O6
6 carbon atoms
12 hydrogen atoms
6 oxygen atoms
And, now for fun….a bit of trivia
Guess how many molecules you weigh!
Amazingly, someone weighing 100 pounds, has
about 916,778,800,000,000,000,000,000,000
molecules making up their body! I had to look it
up how to say that huge number here. That's
916 septillion, 778 sextillion, 800 quintillion
molecules in a 100 pound body!!
And Remember
Never Trust an Atom
They make up everything!