1. Mixtures and Compounds

2. Objectives:
Describe the characteristics of mixtures
18-1 Mixtures

3. A mixture is formed when any two elements or
compounds are blended together.
These blended materials touch each other but are not
chemically combined, so a mixture can be physically
separated.
Dirt – a mixture of clay, sand, particles or dead
plants, and water.
Cake and pancake mixes are other familiar mixtures.
Mixture

4. Objectives:
Identify the properties of solutions
Distinguish between solute and solvent
Compare the type of solutions
Describe suspensions
18-2 Solutions

5. Liquid mixtures such as sugar dissolving in water are
called solutions
Solutions have two parts:
Solvent – is the part that dissolves another material
Solute – is the material that is dissolves
For example in the sugar water, water is the solvent and
sugar is the solute.
Solutions

6. When a small amount of solute is dissolved in a
solvent, the solution is called a dilute solution.
If a large amount of solute is dissolved in the
solvent, the solution is said to be a concentrated
solution.
When a solvent has dissolved all the solute it can at its
present temperature, it is called saturated.
Heating and then cooling a solution to dissolve more
solvent is called supersaturated solution.
Solutions

7. Gases and liquids can all be solvents and solutes.
The air we breathe is a solution of nitrogen and oxygen
with other gases dissolved in them
Carbon dioxide gas is dissolved in water to make
carbonated drinks, when you open the bottle the
carbon dioxide bubbles out of the solution.
Metal alloys are solid solutions made by melting and
mixing two of more metals
A suspension is a special type of solution that forms
when a solvent cannot actually dissolve the solute
because the molecules of the solute are larger than the
molecules of the solvent.
Solutions

8. Objectives
Distinguish between compounds and mixtures
Identify common compounds and their formulas
Distinguish between organic and inorganic compounds
18-3 Compounds

9. Compounds occur when two or more different kinds
of atoms combine chemically.
Water is composed of two atoms of hydrogen and
one atom of oxygen.
Compounds have physical and chemical properties
that are different from the properties of the elements
from which they are made.
Compounds

10. Compounds are written as chemical formulas, using
the symbols of the elements that combine to make
the compound
Compounds can be classified as organic or inorganic.
Organic compounds always contain carbon. These
compounds can also contain hydrogen, oxygen,
nitrogen, and sulfur.
The remaining noncarbon compounds are called
inorganic because it contains carbon.
Compounds

11. Objectives
Explain what a chemical bond is
Distinguish between covalent, ionic, and metallic bonds,
and give an example or each
Describe valence
18-4 Chemical Bonding

12. The force that binds atoms together is called a
chemical bond
Bonding occurs when atoms gain, lose, or share
electrons in their outer energy level.
There are three common types of chemical bonds:
Covalent
Ionic
Metallic
Chemical Bonding

13. Covalent bonds occur when atoms share electrons
Compounds formed by covalent bonds generally melt
at low temperatures and do not conduct electricity
when in solutions.
Examples include: carbon dioxide, water, ozone,
sugar
Covalent

14. Ionic bonds form when electrons are exchanged between
atoms rather than being shared
Compounds formed by ionic bonds generally melt at high
temperatures and conduct electricity when in a solution
Ions are atoms that gain or lose electrons; they have
different properties than the original atom
Cations, positive ions, form when atoms lose electrons
Anions, negative ions, form when atoms gain electrons
Examples include sodium chloride, iron oxide.
Ionic Bonds

15. Metallic bonds result from the attraction between
positive ions and surrounding electrons.
Metallic bonds are similar to ionic bonds
Examples include copper, gold, silver, mercury
Metallic Bonds

16. Each atom has a specific number of electrons that can
be given or received to form a bond.
This number of electrons is called the atom’s valence.
Chemical Bonding