BIOLOGY Chapter 2 Elements and Compounds

1
BIOLOGYChapter 2--------------------Elements
and Compounds
2
Matter, Mass, and Weight

• Matter An object occupies space and has
  mass.
• Mass The quantity of matter an object has.
• Weight The pull of gravity on an objects
  total mass.

3
Elements

• Element A substance composed only of atoms of
  the same atomic number.

One of more than 100 distinct types of matter
that, singly or in combination, compose all
materials of the universe.
4
Atoms

• Atom The smallest unit into which an element
  can be divided and retain its characteristic
  properties.

One unit of an element.
5
Atoms Basic structure

• Made up of

Protons () Neutrons ( ) (Nucleus) Electrons (-)
6
Atoms Basic structure

• Made up of

Protons () Neutrons ( ) (Nucleus) Electrons (-)
Electrically Neutral if Protons Electrons
7
Atoms Basic structure

• Energy Levels
• (orbitals)

K shell L shell M shell N shell O shell P shell Q
shell
L
M
N
O
P
Q
K
8
OrbitalsHow suborbitals fit in...

• Can be very complex!
• Each energy level has a different number of
  suborbitals and depending on the number and type
  of those orbitals determines the of electrons
  that can be in that energy level.
• The farther away from the nucleus an electron is,
  the more energy it has.

9
Orbitals, cont.How suborbitals fit in...

• For this class we will keep it simple.
• 1st Level (K)- 2 electrons
• 2nd Level (L)- 8 electrons
• 3rd Level(M)- 8 electrons
• 4th Level (N)- 18 electrons
• The first level has to be filled before electrons
  will be allow to start filling the next level and
  so on.

10
OrbitalsHow they fill...

• Take the element sulfur
• Sulfur has 16 protons.
• How many electrons does it have?
• 16!
• Those 16 electrons will fill from the inside out
  until they all have a place...

11
SulfurPlacing the electrons
o
o

• 16 Electrons...

o
o
(K fills first
o
o
o
(L) fills next
o
o
o
o
Then we move to (M, s)...
o
o
o
o
o
12
OrbitalsHow they fill...

• How about the element copper
• Copper has 29 protons.
• How many electrons does it have?
• 29.
• Those 29 electrons will fill from the inside out
  until they all have a place...

13
Atomic Number, Symbol, Mass

• Atomic Number The number of protons found
  in an atom.
• Symbol The abbreviation for an element.
• Atomic Mass Weight of an atom approx.
  the sum of its protons and neutrons.

14
Periodic Table of the Elements

• Beryllium

4
Atomic Number 4
Be
Symbol Be
Name
Beryllium
Atomic Mass 9.0112
9.0112
.
15
Periodic Table of the Elements
9
Be
4
Be
4
Mass Protons Neutrons Whats wrong with this
picture?
Beryllium
9.0112
16
Isotopes

• Neutrons do not equal protons.
• More neutrons than protons.
• Unstable nucleus.
• Radioactive Isotope Isotopes that give off
  energy because neutrons peel off their unstable
  nucleus.

17
Whats wrong with this picture?

• Protons do not equal neutrons. (isotope)
• Protons do not equal electrons.
• What is the electrical charge of this atom?

18
Ions

• Protons do not equal electrons.
• More protons than electrons a positive charge.
• More electrons than protons a negative charge.
• Na

19
Isotopes and Ions

• Isotope An atom that has more neutrons than
  protons.
• Positive Ion An atom that has more protons
  than electrons.
• Negative Ion An atom that has more
  electrons than protons.

20
Elements important for life.

• Oxygen (65 of body by weight)
• Carbon (18)
• Hydrogen (10)
• Nitrogen (3)
• (N.O.C.H.)

21
Elements in Human Body

• Oxygen (65)
• Carbon (18)
• Hydrogen (10)
• Nitrogen (3)
• Calcium (2)
• Phosphorus (1)

• Other 1
• Potassium
• Silicon
• Aluminum
• Iron
• Sodium
• Chlorine
• more...

22
Compounds

• Definition
• Two or more elements in definite proportions that
  are joined together by a chemical bond.
• Two Types of Bonds
• Ionic
• Covalent

23
Ionic Bonds

• Why do they form?
• Octet Rule (Rule of Eight)
• Atoms tend to establish completely full outer
  energy levels. (K fills with 2, L and M generally
  fill with 8.)

24
Ionic Bonds an example

• Chlorine has 17 electrons.
• Orbital K takes the first 2.
• Orbital L takes the next 8.
• Orbital M takes 7.

Sodium has 11 electrons. Orbital K takes the
first 2. Orbital L takes the next 8. Orbital M
takes 1.
25
Ionic Bonds an example

• Chlorine needs one more electron to fill its
  outer shell with 8 electrons. (Octet Rule)

If sodium gives up one electron it will have
eight in its outer level.
26
Ionic Bonds an example

• So it does...

27
Ionic Bonds an example

• Chlorine
• 17 protons
• 18 electrons
• Whats its charge?
• -1 (negative ion)
• Sodium
• 11 protons
• 10 electrons
• Whats its charge?
• 1 (positive ion)

What do you think happens next?
28
Ionic Bonds opposites attract

• The sodium atom and the chloride atoms are
  attracted toward one another because of their
  opposite electrical charges.

The combination makes sodium-chloride, abbreviated
NaCl, commonly known as salt.
29
Ionic Bonds

• Definition
• An attraction between ions of opposite charge.
• These bonds are relatively weak and will easily
  dissolve in water.

30
Compounds

• Definition
• Two or more elements in definite proportions that
  are joined together by a chemical bond.
• Two Types of Bonds
• Ionic
• Covalent

31
Covalent Bonds

• Definition
• A chemical bond formed by the sharing of one or
  more pairs of electrons.
• These bonds can be very strong.
• Most of the structures in the body are made using
  these types of bonds.

32
Molecules

• Definition
• A group of elements held together by covalent
  bonds.
• Example
• Water
• Two hydrogens and one oxygen share two pairs of
  electrons.

33
Covalent Bonds, cont.

• Why do hydrogen and oxygen want to share?
• Answer
• Each wants to fill its outer shell with
  electrons.
• Hydrogen fills with 2.
• Oxygen fills with 8.

34
Covalent Bonds

• Many types of covalent bonds

Double covalent share two pairs.
Single covalent shares one pair.
Triple covalent share three pairs.
35
Single Covalent Share 1 Pair
36
Double Covalent Share 2 Pairs
37
Triple Covalent Share 3 Pairs
38
Chemical Reactions

• Equation
• A formula that describes what happens during a
  chemical reaction.

H2
O2
H2O
O

• Balanced Equation
• The elements on the left side of the equation
  are the same as those on the right.

Notice! States of matter (liquid, solid, gas)
may change during a reaction.
39
Chemical Reactions Terms

• Activation Energy (Energy of Activation)
• The energy needed to make a reaction occur.

• Metabolism
• All chemical changes (reactions) that occur
  within an organism.

40
BIOLOGYChapter 2, cont.--------------------Wat
er,Acids, and Bases
41
Water

• The Cradle of Life
• The Universal Solvent.
• The Polarity of Water.

42
Solutions

• Solution A homogeneous mixture of the
  molecules of two or more substances.

Ex. Water and glucose mixture.
43
Solvent

• Solvent Medium in which a substance is
  dissolved (water).

Water is known as the universal solvent because
most of the chemical reactions necessary for life
take place in water (i.e. water is the solvent).
44
Solutes

• Solutes A compound dissolved in some solution.

Ex. The glucose in the water glucose mixture.
45
Solutions (an example)
Glucose (the solute) will dissolve in water (the
solvent) to make a solution.
46
Solutions, cont.
When will a solute dissolve?
As a general rule, solutes dissolve only in
solvents of similar polarity. For example,
glucose (polar) dissolves in water (also polar)
but not in vegetable oil (non-polar).
47
The Polarity of Water

• Polar molecule A molecule with positively
  and negatively charged ends.

One portion of the molecule will attract
electrons more powerfully than the other end. As
a result, one end of the molecule will carry a
partial negative charge.
48
Polarity
For example

• In a water molecule, one oxygen atom shares
  electrons with two hydrogen atoms.

Do they share equally?
49
Polarity, cont.

• Oxygen and Hydrogen do not share electrons
  equally.

• Oxygen is more electronegative (it attracts
  electrons more heavily) than hydrogen.

50
Polarity, cont.

• The result is that the electrons shared by oxygen
  and hydrogen actually spend more of their time
  nearer the oxygen atom. This gives the oxygen a
  slightly negative charge and leaves hydrogen with
  a slightly positive charge.

Note The charges are only partial. (i.e. not
as large as a full proton or electron would be.
-

51
So what?

• Why does it matter that water is polar?

52
The Polarity of Water

• Water bonds (hydrogen bonds) to itself.
• Water bonds to other molecules.
• Water will group non-polar molecules.
• Water is a powerful solvent.

53
Water acts like a magnet.

• The polar ends of water are attracted to other
  polar molecules.
• For example, the positive end of one water
  molecule will align itself with the negative end
  of another water molecule.

54
Hydrogen Bonds

• The positive or negative end of water will be
  attracted to other polar molecules.
• Weak bonds
• Usually last only 1/100,000,000,000 sec., but
  their cumulative effect can be great.

55
Water Clings

• Cohesion Water attracted to water.
• Adhesion Water attracted to other polar
  molecules.
• Capillary Action water will climb by
  adhering to a surfaces electrical charges.

56
Cohesion

• Example
• Why can bugs walk on water?
• The water molecules cohere to one another
  forming a semi-solid base the insect can walk on
  even though the insect is more dense than water!

57
Adhesion

• Hydrophobic Water-fearing
• Water tends to form hydrogen bonds. When it
  mixes with non-polar molecules, it tends to shun
  them and instead cling to other water molecules.
• Hydrophilic Water-loving.
• Polar compounds will form hydrogen bonds with
  water. This breaks ionic bonds, dissolving the
  compound.

58
Adhesion

• Examples
• Hydrophobic
• If you pour vegetable oil in water, what happens?
• Hydrophilic
• If you put your finger in water, what happens?
• (Lycopodium in water)

59
Water

• Its reactions
• Acids and Bases

60
The Spontaneous Reactions of WaterIonization
2 (H2O)
(H3O)
(OH-)


More H3O Acidic. Less H3O Basic
61
pH

• A measure of the relative concentration of
  hydrogen ions in a solution.
• Values range from 0 to 14.
• Less than 7 is an acid.
• More than 7 is a base.

62
Acids

• A substance that causes an increase in the
  concentration of H ions.
• Tastes sour.
• Tingles the skin.

63
Bases

• A substance that causes a decrease in the
  relative concentration of H ions.
• Also called alkaline.
• Tastes bitter.
• Sometimes slippery or slick feeling.

64
pH in Organisms

• Blood pH must be between 7.0 and 7.8 or death
  will occur (7.4 is ideal).

Homeostasis Maintaining a relatively stable
internal physiological environment.
Enzymes A protein capable of speeding up
chemical reactions without itself being affected
by the process.
Regeneration Growing back a lost body part.
65
BIOLOGYChapter 2, cont.--------------------Org
anic Compounds
66
Organic Compounds

• Pertaining to living things.
• The chemistry of compounds containing carbon.

67
Organic Compounds, cont.

• 4 Types of Organic Compounds
• Carbohydrates
• Lipids
• Proteins
• Nucleic Acids.

68
Carbohydrates

• Three types
• Monosaccharides
• Disaccharides
• Polysaccharides

69
Monosaccharides

• One sugar molecule.
• Carbon Backbone Carbon atoms line up near the
  center of the molecule and other atoms attach to
  them.
• Formula for Simple Sugars C6H12O6

70
C6H12O6 (Glucose)
H
H
H
O
H
O
O
O

• C

C
C
C
C
C
H
H
O
H
O
H
H
H
H
H
71
Monosaccharides

• Three basic types
• Glucose (general sugar)
• Fructose (fruits)
• Galactose (milk)
• Isomer Alternative forms of a molecule that
• have the same formula.

72
Disaccharides

• Two monosaccharides bonded together.
• (Transport sugars.)
• Three types
• Maltose (2 glucose)
• Sucrose (1 glucose, 1 fructose)
• Lactose (1 glucose, 1 galactose)

73
Polysaccharides

• Many monosaccharides bonded together.
• (Storage sugars.)
• Three types
• Starches (plants potato!).
• Cellulose (structure plant cell walls).
• Glycogen (animal storage).

74
Functions of Carbohydrates

• Energy source (glucose).
• Long-term energy storage (starch, glycogen).
• Structure (cellulose).

75
Organic Compounds

• 4 Types of Organic Compounds
• Carbohydrates
• Lipids
• Proteins
• Nucleic Acids.

76
Lipids

• Five types
• Fats
• Oils
• Waxes
• Phospholipids
• Steroids

77
Lipids

• Functions
• Long-term energy storage (fats, oils).
• Insulation (fat).
• Protection (waxes waterproof or keep in water).
• Cell membrane structure (phospholipids).
• Control of body functions (steroids).

78
Organic Compounds

• 4 Types of Organic Compounds
• Carbohydrates
• Lipids
• Proteins
• Nucleic Acids.

79
Proteins

• Types
• Amino acids.
• Dipeptides.
• Polypeptides.

80
Proteins

• Amino Acids
• Building blocks for all proteins.
• 20 total.
• Link together to form peptide bonds.

81
Proteins

• Types
• Amino acids single-unit of protein.
• Dipeptides two amino acids linked together.
• Polypeptides many amino acids linked together.

82
Proteins

• Functions
• Movement
• Structure
• Regulation (catalysts, enzymes)
• Transport
• Nutrition
• Defense

83
Proteins(catalysts and enzymes)

• Catalyst Substances used in small amounts which
  speed up chemical reactions without themselves
  being affected by the reaction.
• Enzyme Proteins that function as catalysts.
• (overhead)

84
Enzymes, cont.

• Active sites
• Function by lowering the required activation
  energy.

85
Organic Compounds

• 4 Types of Organic Compounds
• Carbohydrates
• Lipids
• Proteins
• Nucleic Acids.

86
Nucleic Acids

• Types
• DNA (deoxyribonucleic acid)
• RNA (ribonucleic acid)

87
Functions of Nucleic Acids

• Information storage (DNA)
• Information transfer (RNA carries genetic
  information from DNA to ribosomes)