Chemical Bonding Mixtures and Compounds

1
Chemical Bonding/ Mixtures and Compounds

• Biochemistry Unit

2
Definitions
Bond - joins two atoms togetherThe Octet Rule-
Says that atoms tend to gain, lose or share
electrons so as to have eight electrons in their
outer electron shell. -To be stable atoms must
have their outer orbit filled. -Usually the
outer orbit holds 8 electrons -Hydrogen and
Helium have an outer orbit that only holds 2
electrons. Chemical bond a force that holds
two atoms together (occurs because atoms want to
achieve stability ) atoms want to have a complete
outermost energy level
3
Types of bonds

• Ionic bonding bonding that involves a transfer
  of electrons (one atom gains electrons and one
  atom loses electrons) ions are formed
• Electrons have a -1 charge
• A positive ion is formed when a electron is given
  off
• A negative ion is formed when a electron is
  gained

4
Types of Bonds

• Covalent bonding - occurs when atoms share
  electrons to fill outer orbits. Water is 2
  Hydrogen and 1 Oxygen covalently bonded.

5
Covalent bonding

• Electrons in a covalently bonded compound are not
  shared equally
• Larger atoms tend to hog more electrons.
• In water Oxygen hogs
• more of the electrons and
• therefore the oxygen side
• is more negative and the
• hydrogen side is slightly
• positive
• -When there are different
• charged sides the molecule
• is said to be polar.

- side
side
6
Hydrogen Bonds

• Attraction that forms between two polar molecules
  (when hydrogen is present).
• The positive side of one polar molecule attracts
  and is bonded to the negative side of another
  polar molecule.

7
Van der Waals Forces

• Van der Waals forces- A slight attraction that
  occurs when two oppositely charged regions of
  nearby molecules are close together

8
Compound

• A substance formed by the combination of two or
  more elements in definite proportions.
• Exp NaCl, Salt

9
Mixture

• Mixture - which are materials composed of two or
  more elements or compounds that are physically
  mixed together, but not chemically combined.
• Exp salt water, chocolate chip cookie,

10
Solutions and Suspensions

• Solutions and Suspensions are types of mixtures
• Solutions are the mixtures of two or more
  substances which are physically mixed together
  but not chemically combined
• Suspensions mixtures of liquid and
  non-dissolved materials.

11
Solution

• Solute- the substance that is dissolved
• Solvent- The substance being dissolved