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Elements and Compounds
Warm Up Activity This picture show the atoms that are
present in the air.
1. Which ones are elements?
2. How can you tell?
What do we call these
things?
An Atom
3 Atoms
What do we call these
things?
6 Atoms which
happen to be of 3
different elements
What do we call these
things?
A Molecule
• We don’t call it “2 atoms joined
together” we say it is one molecule.
• Since the atoms are the same, it is
also an element, not a compound.
What do we call these
things?
A Molecule of a
compound
2 molecules of a
compound
* Notice that these
molecules have
different atoms in
them, so they are
compounds, not
elements.
Some of the elements in air go around
as single atoms (such as argon).
Or as molecules such as oxygen.
Compounds go around as molecules.
Since there is just one atom, you
would write: Ar
Since there are two atoms of the
same element, you would write O2
Since there are different elements,
you would list both: H2O.
Ar
O H
H
Since there’s 2
oxygen atoms, you
write a “2” after the
O
O
O
If there’s just one
atom, don’t put a
number after it!
( Gas)
One Element
This one likes to go round
in pairs as a gas.
(molecules)
This a COMPOUND of
two different elements
Notice there are
two different
types of atoms
joined together.
That’s what
makes this a
compound.
Element or
Compound?
Element
Element or
Compound?
Compound
Element or
Compound?
Compound