Chapter 2 Section 1 Notes
What is Matter?
Chemistry
Chemistry: The study of matter and how it
changes
Examples of how we use chemistry
everyday:
 Cell phones
 soap
 food
 clothes
Matter
 Matter: anything that
has mass and takes
up space
 Examples of matter:
 people
 rocks
 air
 The following are
NOT matter because:
they have no mass &
don’t take up space




light
sound
electricity
time
Elements
 Elements: substances
that cannot be broken
down into simpler
substances
 Examples:
 Helium
 Silver
 Neon
 If it is on the
PERIODIC TABLE of
the ELEMENTS, it’s an
element!
Elements are made up of atoms.
Atoms: smallest particle of an element that
still has properties of an element
Examples of substances made of atoms of
the same element:
 Diamonds: made of carbon
 Foil: made of aluminum
Elements on the Periodic Table:
 In 1760, there were only 16 known elements
because scientists at the time weren’t clear of
the nature of gases. Each element has its
own symbol, made up on one or two letters.
If there are 2 letters, the first one is ALWAYS
capital and the second is ALWAYS
lowercase. The current standard table
contains 118 confirmed elements. Each
element behaves differently & uniquely from
each other.
Examples:
 Hydrogen: H
 Carbon: C
 Oxygen: O
 Sodium: Na
 Gold: Au
Compounds
 Compounds: substances made of atoms of
more than 1 element joined together.
 Examples:
 Sugar: C12H22O11: Made of the elements
carbon, hydrogen, and oxygen.
 Human Body: contains oxygen, nitrogen,
sulfur, phosphorus, hydrogen, etc. (Most of
the elements exist as compounds instead of
as free elements floating in the body.)
Compounds
Every compound is unique and different
from the elements it is made from. Think
of NaCl.
Picture of
Chlorine gas
Picture of
Sodium metal
Picture of table
salt
Molecules
 Molecules: smallest
unit of a compound
that still behaves like
the compound.
 Examples:
 Water, H2O, is 1
molecule of water; if
you take away an
atom of hydrogen or
oxygen, it is no longer
water.
 Oxygen, O2
molecules can also
be made of atoms of
the same element
 O2 is called a diatomic
molecule
Chemical Formula
Chemical Formula: the chemical symbols
and numbers indicating the atoms
contained in the basic unit of a substance.
Subscripts
 Subscripts: tells the number of atoms of each
element in a compound.
 Examples:
 H2O water, contains 2 hydrogen atoms and 1
oxygen atom
 CO2 carbon dioxide, contains 1 carbon atoms
and 2 oxygen atoms
 C3H8O rubbing alcohol, contains 3 carbon
atoms, 8 hydrogen atoms, and 1 oxygen atom.
 3CO2: the number in front is called a coefficient
and tells how many molecules there are of that
compound.
Pure Substances
 Pure substance: any matter that has a
fixed composition and definite properties
 There are 2 types of pure substances:
1. Elements
2. Compounds
Pure Substances
Examples of pure substances:
 Carbon – element
 Methane, CH4 – compound
 Silver – element
 Neon – element
 Carbon dioxide, CO2 – compound
 Water, H2O - compound
Mixtures
Mixtures: a combination of pure
substances; can be physically separated
into parts
Examples
 salad: can separate lettuce, tomato, onion
 grape juice
 air we breathe: 78% Nitrogen, 21% Oxygen
(other 1% carbon dioxide, argon, helium, and
neon)
There are 2 types of mixtures:
1. Homogeneous mixtures: mixtures that
are uniformly mixed
 Examples: salt water, kool-aid, air we
breathe
 We say that homogeneous mixtures are
miscible, which means solids, liquids, or
gases that can be mixed
There are 2 types of mixtures:
(continued)
2. Heterogeneous mixtures: mixtures that
are NOT uniformly mixed
 Examples: flour and water, Italian
dressing
 We say that heterogeneous mixtures are
immiscible, which means they don’t
completely mix, can often see layers
Graphic Organizer for Matter
Matter
Pure
Substances
Elements
Compounds
Mixtures
Homogeneous
Mixture
Heterogeneous
Mixture