Chemicals Of Life I

1
Chemicals Of Life I

• The Structure of Matter

2
Section One

• Molecules and Atoms

3
A Simple Question...

• What happens if you divide the flower below into
  smaller and smaller parts?
• What happens if you divide a sugar cube below
  into smaller and smaller parts?
• Eventually, they become too small to divide
  further!

4
Matter

• Matter is anything that occupies space and has
  mass.
• Suppose you have a piece of matter, such as a
  brick, and you divide it into many parts.
• Although the pieces of this brick are smaller,
  they consist of the same material and retain the
  same properties as the original brick.
• Now suppose you subdivide a glucose sugar cube.
• If you continue to divide the cube, you would
  eventually reach one particle of sugar, a
  molecule.

5
Molecule

• A molecule is the smallest part of a substance
  having the properties of that substance.
• If you could greatly magnify a sugar molecule,
  what would it look like?
• One sugar molecule a glucose structure

6
A Question

• Imagine tasting a single molecule of sugar.
• How does one molecule of sugar taste?
• A. Different, because of its new composition.
• B. Like the original sugar cube.
• C. Has no taste at all.
• Answer B The chemical properties of a
  substance are retained by the molecule.

7
Sugar Molecule

• If you chemically decompose the sugar molecule
  into its three basic parts (carbon, hydrogen,
  oxygen), it loses its original properties.
• How many of the following atoms are present in
  the glucose molecule? Carbon
  Hydrogen Oxygen
• 6
  12 6
• The formula for glucose is C6H12O6.

8
Information

• You now know that a glucose molecule is composed
  of carbon, hydrogen and oxygen.
• Atoms are the basic units composing a molecule.
• An atom is the smallest part of an element with
  the properties of that element.
• There are 92 naturally occurring elements.
• Elements can combine in a variety of ways to form
  different compounds.
• A compound is a substance composed of 2 or more
  elements chemically combined in definite
  proportions by weight.
• A formula is a representation of a compound using
  symbols and subscripts (if necessary).

9
C, H and O

• There are many possible combinations of carbon,
  hydrogen and oxygen.
• These are some of the combinations
• Carbonic Acid (H2CO3)
• Sucrose (C12H22O11)
• Ethyl Alcohol (C2H5OH)
• Vinegar (CH3COOH)
• These are examples of compounds found in living
  things. They are called organic compounds.
• These are only a few of the many organic
  compounds that can be made with these
  elements.

10
Information

• A subscript is the number at the lower right side
  of a symbol in a formula.
• It indicates the number of atoms of an element
  present in the molecule.
• If there is no subscript, there is only one atom
  of the element present.

11
Formulas

• Using the formulas below, indicate the number of
  atoms of each element in each organic compound.

Compound C H O
H2CO3 1 2 3
C12H22O11 12 22 11
C2H5OH 2 6 1
CH3COOH 2 4 2
12
Information

• An atom is about one four-millionth of a
  centimeter in diameter.
• When compared to a cubic centimeter, it is such a
  small volume that it is proportional to a speck
  of dust in a football stadium.

13
Review

• Matter is anything that has mass and occupies
  space.
• A molecule is the smallest part of a substance
  having the properties of that substance.
• Elements are substances that cannot be broken
  down by ordinary chemical means.
• An atom is the smallest part of an element with
  the properties of that element.
• A compound is a substance composed of two or
  more elements chemically combined in definite
  proportions by weight.

14
Quiz Fill In The Blanks
Scientists have determined that _____________ is
anything that has mass and occupies space. They
also have identified the ___________ as the
smallest particle of an element (a substance that
cannot be broken down by ordinary chemical
means). A substance composed of two or more
elements that are chemically combined is called
a(n) ____________. The smallest particle of this
substance that has the properties of the
substance is a(n) ___________.
matter
atom
compound
molecule
15
Section Two

• The Bohr Model

16
The Atom

• Lets look at what 100 years of experimentation
  have taught us about the atom and its electrical
  nature.
• Nucleus The central part of the atom that is
  composed of protons and neutrons.
• Orbits The paths electrons take about the
  nucleus.
• Protons Positive particles in the nucleus mass
  approximately 1 hydrogen atom.
• Neutrons Particles found in the nucleus having
  no electrical charge mass approximately 1
  hydrogen atom.
• Electrons Negative particles that revolve about
  the nucleus in orbits mass
  1/1837th of a hydrogen atom.

17
The Atom

• Lets look at a typical atom using the theories
  of John Dalton, Niels Bohr, Sir Joseph Thompson,
  Ernest Rutherford and James Chadwick.
• The representation of the atom is called the Bohr
  Model (a picture of the atom developed by Niels
  Bohr).
• Helium Atom?
• The nucleus is the central
  portion of the atom.
• The nucleus is composed of protons and neutrons.

18
The Atom

• Protons are particles that have a positive ()
  charge and a mass about equal to one atom of
  hydrogen (approximately 1).
• Neutrons are particles that have no electrical
  charge but a mass about equal to the mass of a
  proton. Hydrogen is the only element without
  neutrons.
• The nucleus of the atom is surrounded by one or
  more electrons.
• Electrons are particles with anegative charge
  and a massequal to 1/1837th of a hydrogenatom
  (virtually 0).
• Each orbit is an unchanging pathor energy level.

19
Question

• Looking at the picture of the Helium atom below,
  what is the total charge of this atom?
• A. Positive
• B. Negative
• C. Neutral
• Answer C because the proton number electron
  number.
• In all atoms, the number ofpositive charges
  equals thenumber of negative charges.
• Therefore, all atoms areelectrically neutral.

20
Select The Correct Answer
A. neutron D. nucleus B. orbit E. hydrogen C. proton F. electron

• Positively charged particles found in the nucleus
  of atoms are ______________.
• Negatively charged particles that orbit the
  nucleus are ________________.
• The nucleus of an atom is composed of protons ()
  and _______________ (0).
• The _______________ has a () charge and may
  contain neutrons.

21
Answers

• Positively charged particles found in the nucleus
  of atoms are ______________.
• Negatively charged particles that orbit the
  nucleus are ________________.
• The nucleus of an atom is composed of protons ()
  and _______________ (0).
• The _______________ has a () charge and may
  contain neutrons.

protons
electrons
neutrons
nucleus
22
Energy Levels

• The orbits or energy levels in which electrons
  revolve are identified by letters.
• First Energy Level K
• Second Level L
• Third Level M
• Fourth Level N
• Orbits, or energy levels,are filled in order
  fromK to L to M.
• When filled, the orbits closerto the nucleus
  hold fewerelectrons. The orbits farther
  fromthe nucleus hold more electrons.

N
M
L
K
Nucleus
23
Energy Levels

• K energy level can hold 2 electrons.
• L energy level can hold up to 8 electrons.
• M energy level can hold up to 18 electrons.
• N energy level can hold up to 32 electrons.
• Each orbit can hold less than its maximum number
  of electrons, but never more.
• The sum of all of the electrons in the orbits
  must be the same as the total number of electrons.

Total Electrons K L M
1 1 0 0
5 2 3 0
8 2 6 0
10 2 8 0
18 2 8 8
24
Quiz Fill In The Blanks
Niels Bohr, the famous Danish scientist,
developed a model for the atom. In it, negative
particles called __________ travel in orbits
around a positively charged nucleus. The
____________ (K) orbit usually contains two
negative particles. The nucleus is composed of
positive particles, called ____________, and
neutral particles, called ___________. These
three particles and the atoms that they compose
form all matter.
electrons
first
protons
neutrons
25
Section Three

• How To Draw An Atom

26
Bohr Model

• This section shows you how to draw a
  representation of an atom using the Bohr model.
• You now know that atoms have a positive center
  called a nucleus that contains protons and
  usually neutrons.
• You also know that electrons revolve about the
  nucleus in definite orbits.

27
Periodic Table

• The periodic table is a classification of
  elements according to atomic number.
• Here is a sample from the periodic table that
  contains the information needed to draw an atom.

6.939 Li 3
28
Periodic Table

• The universal symbol (abbreviation) for the
  element is found in the center. This elements
  symbol is Li.
• The atomic number is the number of protons in the
  atom and is found at the bottom of the box. The
  atomic number is 3.
• The atomic mass is the total mass of the atom and
  is found at the top of the box. You round it off
  to a whole number. The atomic mass is 7.
• Using the information from the periodic table,
  you can draw the atom.

6.939 Li 3
29
Proton, Neutron Electron

• Before you can draw the atom, you first need to
  know the number of protons, neutrons and
  electrons.
• Then number of protons is given by the atomic
  number. Therefore, P 3.
• The number of electrons is the same as the number
  of protons. Therefore, E 3.
• The number of neutrons is obtained by subtracting
  the atomic number from the atomic mass.
• Atomic mass 7- Atomic number 3
• Neutrons 4 Therefore, N 4.

6.939 Li 3
30
Lithium Atom

• Using the information you derived, you now can
  draw a lithium (Li) atom.

3P4N
31
Neon Atom

• How many protons are in the nucleus?
• Protons 10.
• How many electrons are in the orbits?
• Electrons 10.
• How many neutrons are in the nucleus?
• Neutrons 10.
• You are now ready to draw the neon atom using the
  information derived from the periodic table.
• P 10 E 10 N 10

20.183 Ne 10
32
Neon Atom
P 10 E 10 N 10
20.183 Ne 10
10P10N
33
Hydrogen Atom

• Symbol H
• Atomic Number 1
• Atomic Mass 1
• Nucleus Protons 1
• Nucleus Neutrons 0
• Electrons in main orbits (levels)
• K 1
• L 0
• M 0
• N 0

1P
1.00797 H 1
34
Review

• Symbols are abbreviations used to represent
  elements.
• The periodic table is a classification of
  elements according to atomic number.
• The atomic number equals the number of protons in
  an atom.
• The atomic mass equals the number of protons plus
  the number of neutrons in an atom.
• The neutron number equals the atomic mass minus
  the atomic number.
• The electron number equals the proton number in
  atoms.

35
Select The Correct Answer
A. symbols D. periodic B. inert E. orbits C. mass F. number

• The atomic _______________ is the total number of
  protons and neutrons in an atom.
• The atomic _______________ is the number of
  protons in an atom.
• The letters used to represent elements are called
  _______________.
• The _______________ table is a classification of
  all the known elements.

36
Answers
mass

• The atomic _______________ is the total number of
  protons and neutrons in an atom.
• The atomic _______________ is the number of
  protons in an atom.
• The letters used to represent elements are called
  _______________.
• The _______________ table is a classification of
  all the known elements.

number
symbols
periodic
37
Section Four

• Ions and Charges

38
Information About Atoms

• All atoms are electrically neutral.
• The outer orbit of an atom is called the valence
  orbit.
• The electrons found in the valence orbit are
  valence electrons.
• The valence electrons are involved in the
  formation of chemical compounds.
• Elements with stable valence orbits usually do
  not react to form compounds these elements are
  inert.

39
Valence Orbits

• How many electrons are found in each of these
  elements valence orbits?
• Oxygen 6
• Neon 8

10P10N
8P8N
Neon
Oxygen
40
Inert Elements

• These elements are inert. How many electrons are
  found in these elements valence orbits?
• Argon 8
• Helium 2
• The inert elements havestable valence orbits.
• A stable valence orbitis one that is unlikelyto
  change.
• When other atoms,which are not inert,combine to
  form compounds, stablevalence orbits form.

18P22N
2P 2N
Argon
Helium
41
Sodium Atom

• We can use numbers to represent the electrons on
  each orbit.
• It requires less energy for sodium tolose 1
  electron than gain 7 electrons.
• Sodium loses 1 electron.
• Sodium would now have11 protons and 10
  electrons.
• What is the charge on thesodium ion?
• Answer 1
• Sodium is now an ion.

11P12N
2
8
1
X
Sodium
42
Sodium Ion

• Sodium is now an ion.
• It is no longer an atom becauseall atoms are
  electricallyneutral.
• Lets examine some otheratoms and ions.

1
11P12N
2
8
Sodium
43
Magnesium Atom

• It requires less energy for magnesium to lose 2
  electrons than gain 6 electrons.
• Magnesium loses 2 electrons.
• Magnesium now has12 protons and 10 electrons.
• What is the charge on themagnesium ion?
• Answer 2

12P12N
2
8
2
Magnesium
44
Magnesium Ion

• Magnesium is now an ion.

2
12P12N
2
8
Magnesium
45
Information

• Atoms with 1, 2 or 3 electrons in their valence
  orbits are metals.
• Metals lose electrons to form positive ions.

46
Phosphorus Atom

• It requires less energy for phosphorus to gain 3
  electrons than lose 5 electrons.
• Phosphorus gains 3 electrons.
• Phosphorus now has15 protons and 18 electrons.
• What is the charge on thephosphorus ion?
• Answer -3

15P16N
2
8
5
Phosphorus
47
Phosphorus Ion

• Phosphorus is now an ion.

-3
15P16N
2
8
8
Phosphorus
48
Sulfur Atom

• It requires less energy for sulfur to gain 2
  electrons than lose 6 electrons.
• Sulfur gains 2 electrons.
• Sulfur now has 16 protonsand 18 electrons.
• What is the charge on thesulfur ion?
• Answer -2

16P18N
2
8
6
Sulfur
49
Sulfur Ion

• Sulfur is now an ion.

-2
16P18N
2
8
8
Sulfur
50
Information

• Atoms with 5, 6 or 7 electrons in their valence
  orbits are nonmetals.
• Nonmetals gain electrons to form negative ions.
• The charge on an ion is its valence or oxidation
  state.

51
Summary Table
Valence Electrons Electrons Gained Electrons Lost Oxidation State
3 0 3 3
7 1 0 -1
8 0 0 0
5 3 0 -3
6 2 0 -2
52
Information

• Atoms with 4 electrons in their valence orbits
  can act either as metals or nonmetals.
• These atoms tend to share electrons with other
  atoms.

53
Carbon

• Carbon is a good example of an atom that shares
  electrons.
• Carbon atoms often combine with other carbon
  atoms.
• In this case, two carbon atoms share a pair of
  electrons.

6P6N
6P6N
Carbon
Carbon
54
Carbon

• You can represent these electrons with numbers.

6P6N
6P6N
3
2
2
3
2
Carbon
Carbon
55
Review

• Inert elements have stable valence orbits and do
  not react to form compounds.
• Atoms are electrically neutral.
• Ions are charged atoms.
• An atom that loses an electron becomes a positive
  ion.
• An atom that gains an electron becomes a negative
  ion.

56
Select The Correct Answer
A. inert D. ion B. orbit E. metals C. positive F. neutral

• When an atom loses electrons it becomes a
  ________________ ion.
• Atoms are electrically ________________.
• Elements with stable valence orbits are
  ______________.
• A charged atom is called a(n) _________________.

57
Answers
positive

• When an atom loses electrons it becomes a
  ________________ ion.
• Atoms are electrically ________________.
• Elements with stable valence orbits are
  ______________.
• A charged atom is called a(n) _________________.

neutral
inert
ion
58
Section Five

• Ionic and Covalent Bonding

59
Ionic Bonds

• The transfer of electrons from one atom to
  another produces charged particles called ions.
• The ions are attracted to each other forming an
  ionic bond.
• In this example, magnesium loses electrons and
  oxygen gains electrons.
  
  (Two electrons transfer.)

12P12N
8P8N
Oxygen
Magnesium
60
Ionic Bonds

• The charge on the magnesium ion is 2.
• The charge on the oxygen ion is -2.
• The metal ion is magnesium the nonmetal ion is
  oxygen.
• The formula is MgO.

-2
2
12P12N
8P8N
Oxygen Ion
Magnesium Ion
61
Calcium and Chlorine
17P18N
17P18N
Calcium
Chlorine
12P12N
Chlorine
62
Calcium and Chlorine

• Calcium loses two electrons, the chlorine gains
  one electron.
• Two chlorine atoms are required to accept the two
  electrons.
• The oxidation state of the calcium ion is 2.
  The oxidation state of the chlorine ion is -1.
• The total charge on the compound is 0.
• The charge on calcium is 2, the charge on each
  chlorine is -1. (2) (-1) (-1) 0
• The formula is CaCl2.

63
Organic Compounds

• Organic compounds are found in living things.
  Many organic compounds contain only carbon and
  hydrogen atoms.
• Hydrogen has one valence electron.
• Carbon has four valence electrons.
• Carbon and hydrogen share pairs of electrons by
  forming covalent bonds.
• Carbon can form up to four covalent bonds with
  hydrogen atoms. This organic compound has
  the formula CH4 and is called methane.

64
Methane (CH4)
1P
1P
6P6N
1P
1P
Carbon
65
Review

• All compounds are electrically neutral.
• Metals lose electrons and form positive ions.
• Nonmetals gain electrons and form negative ions.
• An ionic bond forms when electrons transfer
  between atoms.
• A covalent bond forms when a pair of electrons is
  shared by atoms.

66
Select The Correct Answer
A. neutral D. covalent B. negative E. inert C. ionic F. positive

• A(n) _______________ bond forms when electrons
  transfer.
• If an atom loses electrons, it becomes an ion
  with a(n) _______________ charge.
• All compounds are electrically _________________.
• A(n) ________________ bond forms when there are
  shared pairs of electrons.

67
Answers
ionic

• A(n) _______________ bond forms when electrons
  transfer.
• If an atom loses electrons, it becomes an ion
  with a(n) _______________ charge.
• All compounds are electrically _________________.
• A(n) ________________ bond forms when there are
  shared pairs of electrons.

positive
neutral
covalent
68
Section Six

• Testing Your Knowledge

69
Test of What You Learned

• There are 10 questions on this test.
• Try to correctly answer all of the questions.
• If you miss a question, watch the screen for an
  explanation of the correct answer.

70
Select Best Choice
Answer Column Negative, in nucleus Electrons and neutrons Negative, in orbit Positive, in nucleus No charge, in nucleus Positive, in orbit No charge, in orbit Protons and neutrons

• Electron

Correct Answer C An electron is the negatively
charged particle that orbits the nucleus in the
Bohr atom. Its mass equals 1/1837th of a
hydrogen atom.

• Proton

Correct Answer D A proton is the positively
charged particle found in the nucleus of the Bohr
atom. Its mass is approximately equal to one
hydrogen atom.
71
Select Best Choice
Answer Column Negative, in nucleus Electrons and neutrons Negative, in orbit Positive, in nucleus No charge, in nucleus Positive, in orbit No charge, in orbit Protons and neutrons

• Neutron

Correct Answer E A neutron is the neutral (no
charge) particle found in the nucleus of the Bohr
atom. Its mass is approximately equal to one
hydrogen atom.

• Nucleus

Correct Answer H A nucleus is the structure
composed of protons and neutrons that is found in
the center of the Bohr atom. It always has a
positive charge.
72
Select The Best Choice

• Positive ions are to metals as negative ions are
  to ____________.
• A. protons
• B. metals
• C. nonmetals
• D. electrons
• E. Stable orbits

nonmetals
Since metals become positive ions when they lose
electrons, the best analogy is nonmetals, which
become negative ions when they gain
electrons.
73
Select The Best Choice

• Atomic number is to protons as atomic weight is
  to ____________________.
• A. electrons
• B. neutrons
• C. nucleus neutrons
• D. electrons protons
• E. protons neutrons

protons neutrons
Since an atomic number is determined by the
number of protons, the best analogy is protons
neutrons, which determine the atomic weight.
74
Fill In The Blanks
The type of bonding that takes place within a
molecule determines some of the characteristics
of the substance it makes up. Atoms that gain or
lose electrons and become charged are called
__________. They form ___________ bonds when the
electron transfer takes place. This is very
different from a type of bond that is found in
organic compounds. The atoms in organic
molecules that share a(n) __________ of electrons
form a(n) ___________ bond.
ions
ionic
pair
covalent
75
Chemicals Of Life I
Biology Basics
Review!
You Have Completed...

• The Structure of Matter