CLASSIFICATION of MATTER
All matter is made up by ATOMS
In nature, atoms are found by three different forms:
SINGLE ATOMS
MOLECULES
CRYSTAL LATTICES
This is the case of noble
gases.
Ex: Helium, He
Group of atoms bonded together
in a fixed proportion. Atoms can be
of the same or different type.
Ex: oxygen O2, water H2O
Huge,undefined number of atoms
bonded together in a geometric
pattern that is repeated in three
dimensions Atoms can be of the
dimensions.
same or different type.
All matter can be classified in two groups: pure substances and mixtures
PURE SUBSTANCES
This is a type of matter that cannotbe decomposed into simpler ones by physical methods.
methods It has
constant composition.
There two types of pure substances
ELEMENTS
It is a substance that only
nly contains one type of
atom. It cannot be decomposed into other
simpler ones that are different.
The atoms are either separated (noble gases)
or grouped in molecules (H2) or crystals
(diamond or graph
phite)
Copper is an element
(Cu). Even if it changes
state or it is divided, its
composition does not
change. It is cannot be
decomposed into simpler
substances.
COMPOUNDS
are substances that contains two o more
types of atoms joined together. It can be
decomposed into different ones via chemical
changes. In liquid and gases, the atoms are
together in molecules (H2O, NH3). In solids,
atoms can be arranged in crystal lattices.
Bell peppers can be decomposed during
digestion into different compounds such as
carbohydrates, vitamins, fibre that our body
transforms into simpler substances via
chemical changes.
QUESTIONS
1. Are the following particles elements or compounds?
a. A water molecule
b. An oxygen molecule
c. A neon atom
2. Are these crystal elements or compounds?
a. Salt
b. Diamond
c. Copper sulphate crystals (CuSO4)
3. Are these statements true or false?
a. An element can be formed of molecules or crystals
b. A compound can be made of single atoms
4. Look at the pictures and decide whether they correspond to an element or a compound.Use
expressions like:
- I think is an element because...
- This must be a compound because...
- I can see here two different atoms bond together so...
5. Look at the picture and say what each one is
a. A compound that forms a crystal lattice
b. A monoatomic element
c. An element that forms a crystal lattice
d. A compound that forms a molecule.