The Chemistry of Life

1
The Chemistry of Life

• Biochemistry Unit
• Chapter 6
• Section 1

2
Elements

• An element is a substance that cant be broken
  down into simpler substances.
• 90 elements occur naturally on Earth.

3
Important Elements

• 25 elements are essential to the living things.
• The 4 most important are Carbon, Hydrogen,
  Oxygen, and Nitrogen (CHON) which make up 96 of
  a human
• Trace elements are elements that are needed by
  living things in small amounts iron, iodine,
  fluorine...

4
The Periodic Table of the Elements

• Elements are arranged in a table called the
  Periodic Table of the Elements

5
Periodic Table
Atomic Number protons electrons
Neutrons Atomic mass- Atomic Number 11-56
Neutrons
6
Atoms Building Blocks of Elements

• An atom is the smallest particle of an element
  that still has the characteristics of that
  element.

7
Atomic Structure

• The center of the atom is called the nucleus
• It is surrounded by an electron cloud.

8
Sub-atomic particles

• There are 3 subatomic particles you need to know

Location Charge Number
Proton Nucleus Positive Atomic Number
Neutron Nucleus Neutral Mass (minus) Atomic number
Electron Electron Cloud Negative Atomic Number
9
Look at your periodic table...

• How many protons, electrons, and neutrons does
  each of the following elements have?

Protons Electrons Neutrons
Carbon
Nitrogen
Gold
10
Electrons

• Electrons travel around the nucleus in energy
  levels.
• The first level holds 2 electrons.
• The second level holds 8 electrons.
• The third level holds 18 electrons.

11
Isotopes

• Atoms of the same element that have different
  numbers of neutrons are called isotopes.
• Carbon-12 has an atomic mass of 12 and an atomic
  number of 6.
• It has 6 protons, 6 electrons, and 6 neutrons.
• Carbon-13 has one extra neutron, for a total of
  7.

12
Compounds and Bonding

• A compound is made of atoms of two or more
  elements combined.
• Water is a compound (H2O) because it is made of 2
  hydrogen atoms and 1 oxygen atom.
• Carbon Dioxide (CO2) is made of one carbon atom
  and 2 oxygen atoms.

13
Bonds

• Covalent bonds form when 2 or more atoms SHARE
  electrons.
• Ionic bonds form when atoms either gain or lose
  electrons.

14
Bonds

• A molecule is a group of atoms held together by
  covalent bonds, and has no overall charge.
• An ion is a charged particle.
• If an atom gains an electron, it becomes more
  NEGATIVE
• If an atom loses an electron, it becomes more
  POSITIVE

15
Mixtures and Solutions

• A mixture is a combination of substances in which
  the individual components retain their own
  properties.
• For example, if you mixed sand and sugar, you
  could still tell the individual grains apart.

16
Mixtures and Solutions

• A solution is a combination of substances in
  which the individual components combine and form
  a new, different substance.
• For example, Kool-aid powder dissolves in water
  to make a tasty drink.

17
Acids and Bases

• The pH is a measure of how acidic or basic a
  solution is.
• pH can be from 0 to 14.

18
Acids and Bases

• Acids are below 7 (lemon juice, tomatoes). They
  form H ions in water.
• Bases are above 7 (ammonia, drain cleaner, eggs).
  They form OH- ions in water.
• Water is neutral, and has a pH of 7.