1. The Building Blocks of Matter: Atoms- - - + + + + - - + + - - -

2. Matter Anything that has mass and takes up space (volume) Examples:
A brick has mass and takes up space
A desk has mass and takes up space
A pencil has mass and takes up space
Air has mass and takes up space
All of the above examples are considered matter because they have mass and take up space. Can you think of anything that would not be considered matter?

3. What is an atom?
Atoms are the basic building blocks of matter. They make up everything around us; Your desk, the board, your body, everything is made of atoms!
Atoms are too small to see without powerful microscopes.
Atom: the smallest unit of matter that retains the identity of the substance

4. THEORY OF ATOMS

5. Atoms
Smallest possible unit into which matter can be divided, while still maintaining its properties.
Made up of:
protons
neutrons
Electrons - + - + + - + - + -

6. Atomic Structure Atoms are composed of 2 regions:
Nucleus: the center of the atom that contains the mass of the atom
Electron cloud: region that surrounds the nucleus that contains most of the space in the atom
Nucleus
Electron
Cloud

7. The NUCLEUS (The Atom’s “Center”)
Protons and neutrons are grouped together to form the “center” or nucleus of an atom.
Notice that the electrons are not apart of the nucleus + - - -

8. What’s in the Nucleus?
The nucleus contains 2 of the 3 subatomic particles:
Protons
Neutrons

9. What’s in the Electron Cloud?
The 3rd subatomic particle resides outside of the nucleus in the electron cloud
Electron: the subatomic particle with a negative charge and relatively no mass

10. How do these particles interact?
Protons and neutrons live compacted in the tiny positively charged nucleus accounting for most of the mass of the atom
The negatively charged electrons are small and have a relatively small mass but occupy a large volume of space outside the nucleus

11. Atoms are so small that…
it would take a stack of about 50,000 aluminum atoms to equal the thickness of a sheet of aluminum foil from your kitchen.
if you could enlarge a penny until it was as wide as the US, each of its atoms would be only about 3 cm in diameter – about the size of a ping-pong ball
a human hair is about 1 million carbon atoms wide.
a typical human cell contains roughly 1 trillion atoms.
a speck of dust might contain 3x1012 (3 trillion) atoms.
it would take you around 500 years to count the number of atoms in a grain of salt.
C-C-C-C-C-… + 999,995 more
1 trillion atoms  .
Is made of approximately 3 trillion atoms
Just one of these grains

12. + Protons (+) Positively charged particles
Help make up the nucleus of the atom
Help identify the atom (could be considered an atom’s DNA)will never change
Equal to the atomic number of the atom
Contribute to the atomic mass
Equal to the number of electrons (for neutral elements) + - +

13. Neutrons Neutral particles; have no electric charge
Help make up the nucleus of the atom
Contribute to the atomic mass
Can change in numbers when dealing with isotopes + -

14. - Electrons (-) Negatively charged particles
Found outside the nucleus of the atom, in the electron orbits/levels;
Move so rapidly around the nucleus that they create an electron cloud
Mass is insignificant when compared to protons and neutrons
Neutral elements have electrons that are Equal to the number of protons
Involved in the formation of chemical bonds
Electrons can increase or decrease when working with ionic bonding and ions + - -

15. LABELING AN ELEMENT 1

16. Chem Catalyst
What are the two regions that make up an atom? Which subatomic particles belong in each region?

17. How do the subatomic particles balance each other?
In a neutral atom:
The protons = the electrons
If 20 protons are present in an atom then 20 electrons are there to balance the overall charge of the atom—atoms are neutral
The neutrons have no charge; therefore they do not have to equal the number of protons or electrons

18. How do we know the number of subatomic particles in an atom?
Atomic number: this number indicates the number of protons in an atom
Ex: Hydrogen’s atomic number is 1
So hydrogen has 1 proton
Ex: Carbon’s atomic number is 6
So carbon has 6 protons
**The number of protons identifies the atom.
Ex. 2 protons = He, 29 protons = Cu

19. How do we know the number of subatomic particles in an atom?
Mass number: the number of protons and neutrons in the nucleus
Ex: hydrogen can have a mass of 3.
Since it has 1 proton it must have 2 neutrons
# of neutrons = mass # - atomic #

20. + Mass Number + What would be the mass number of this atom? - - -
The total number of protons and neutrons in an atom’s nucleus
Expressed in Atomic Mass Units (amu)
Each proton or neutron has a mass of 1 amu
What would be the mass number of this atom? - +
 3
 4 + -
3 protons + 4 neutrons = a mass number of 7 amu
Why did we not account for the electrons when calculating the mass number? -

21. Determining the number of protons and neutrons
Li has a mass number of 7 and an atomic number of 3
Protons = 3 (same as atomic #)
Neutrons= 7-3 = 4 (mass # - atomic #)
Ne has a mass number of 20 and an atomic number of 10
Protons = 10
Neutrons = = 10

22. What about the electrons?
The electrons are equal to the number of protons
So e- = p = atomic #
Ex: He has a mass # of 4 and an atomic # of 2
p+ = 2
no = 2
e- = 2

23. Determine the number of subatomic particles in the following:
Cl has a mass # of 35 and an atomic # of 17
p+ = 17, no = 18, e- = 17
K has a mass # of 39 and an atomic # of 19
P+ = 19, no = 20 e- = 19

24. Bohr Models
Niels Bohr created a visual model of the atom to make them easy to understand
A Bohr Model contains a central nucleus surrounded by electron shells
For each model you state the number of protons and neutrons in the nucleus and draw a dot on the electron shells for each electron

25. + Chem Catalyst Which atom is represented below? How do you know? - -

26. How exactly are the particles arranged?
Bohr Model of the atom:
Reviewers think this could lead to misconceptions!
All of the protons and the neutrons
The 3rd ring can hold up to 18 e-
The 1st ring can hold up to 2 e-
The 4th ring and any after can hold up to 32 e-
The 2nd ring can hold up to 8 e-

27. What does carbon look like?
Mass # = 12 atomic # = 6
p+ = 6 no = 6 e- = 6
6 p and 6 n live in the nucleus

28. Chem Catalyst Draw the Bohr Diagram for Potassium
Mass # = atomic # =
p+ = no = e- =

29. Hydrogen (H) Atom - Notice the one electron in the first orbital = 1 +
= 0 -
How many
more electrons
can fit in the 1st
orbital/ level? +
Even though there are no neutrons present,
Hydrogen is still considered an atom

30. Oxygen (O) Atom
Notice the two electrons in the first orbital/level and the six in the second + -
= 8 -
How many
more electrons
can fit in the 2nd
orbital/ level? - + + + - + - - + + - - -

31. Sodium (Na) Atom
Notice the two electrons in the first orbital/level, eight in the second, and one in the third + -
= 11
= 12 - -
How many
more electrons
can fit in the 3rd
orbital/ level? - + + + - + - - + + - - - -

32. Isotopes
Atoms that have the same number of protons, but have different numbers of neutrons
Examples
Notice that each of these atoms have one proton; therefore they are all types of hydrogen. They just have a different mass number (# of neutrons). - - + + + -

34. Isotopes Example:Carbon
Carbon atoms exist naturally with 6, 7 or 8 neutrons. Each atom of carbon has 6 protons.
(mass = mass of protons + mass of neutrons)
These isotopes are called carbon-12, carbon-13 and carbon-14. Alternatively, they may be written 12C, 13C and 14C.
Carbon-12 and carbon-13 are stable. Carbon-14 is unstable

35. Isotope Atomic Stability
The stability of any atom's nucleus depends on the ratio of protons to neutrons. Many isotopes have a ratio of protons to neutrons that renders them unstable and, as a result, they are radioactive.
Radioactive Isotope: An isotope having an unstable nucleus that decomposes spontaneously by emission of a nuclear electron thus achieving a stable nuclear composition.

36. Chem Catalyst How does the arrangement of the periodic table affect the amount of shells an atom has?
After looking at the periodic table, I was able to conclude that the number of shells that an atom contains is based on the row that the element is located in. For example if the element is in row 3, the atom will have 3 electron shells.
It has shells based on its level

37. Draw the bohr diagram for the elements below and come to a conclusion about how the arrangement of the periodic table affects the amount of shells an atom has
Hydrogen
helium
lithium
Beryllium
Boron
Carbon
sodium
Magnesium
Aluminum
Silicon
Potassium
Calcium
Which elements have the same amount of shells? What connection between these makes this possible?
Which elements have the same number of electrons in the outermost shell? What connection between these elements makes this possible?

38. Valence Electrons Electron Shell Number of Electrons 1st 2 2nd 8 3rd
4th 18
5th
6th 32
7th
Noble Gases have full outer electron shells
All other elements have partially filled outer electron shells

39. Periods Each row is called a “period”
The elements in each period have the same number of shells
Period # represents # of shells
1st Period = 1 Shell
2nd Period = 2 Shells
3rd Period = 3 Shells
4th Period = 4 Shells

40. Groups
Each column is called a “group”
The group # represents the # of electrons in an element’s outer orbital(electron shell)
3, 4, 5, 6, 7
The electrons in the outer shell are called “valence electrons”

41. Electron Shells
Each electron shell can hold a certain number of electrons
Electron shells are filled from the inside out
Outermost shell is the highest energy level
Outermost shell represents valence electrons

42. Valence Electrons
Valence electrons are electrons in the outmost shell They are the electrons that are available for bonding.
The electrons in the outer most electron shell are called valence electrons
The shell containing electrons that is furthest from the nucleus is called the valence shell

43. Side note:
As atomic numbers increase, the elements become more rare. They are not just rare in nature, but rare as useful elements, too.

44. Group 1 (alkali metals) have 1 valence electron

45. Hydrogen
Even though it is in group one, Hydrogen is not an alkali metal.
Hydrogen can have the electron traits of two groups: one and seven.

46. Alkali Metals They are very reactive
They all have one electrons in their outer shell. When you are that close to having a full shell, you want to bond with other elements and lose that electron.
An increased desire to bond means you are more reactive.
Fun Fact: when you put some of these pure elements in water (H2O), they can cause huge explosions.

47. Alkali Metals
You will find that the alkali group is shiny and light in weight.
Their light weight and physical properties separate them from other metals.
They are malleable (bendable) and sometimes soft enough to be cut with a dull knife.
Alkali metals are not the type of metals you would use for coins or houses.

48. Group 2 (alkaline earth metals) have 2 valence electrons

49. Chem Catalyst How many valence electrons does nitrogen have?
Draw the Bohr diagram
identify the number of valence electrons, and the number of shells in the atom

50. Alkaline Earth Metals
This is the second most reactive family of elements in the periodic table
Each of them has two electrons in their outer shell. They are ready to give up those two electrons to form bonds.
Do you know why they are called alkaline?
When these compounds are mixed in solutions, they are likely to form solutions with a pH greater than 7. Those higher pH levels means that they are defined as "basic" or "alkaline" solutions.

51. Group 18 (Noble gases) have 8 valence electrons, except helium, which has only 2

52. Noble Gas Stability Noble gases are usually unreactive
This is because they have full valence shells
An element with a full valence shell is a happy element (stable) 

53. Helium Helium (He) is different from all of the other elements.
It is very stable with only two electrons in its outer orbital (valence shell).
Grouped with the noble gases
The noble gases and helium are all "happy," because their valence shell is full.

54. Noble Gases Neon is used in advertising signs.
Argon is used in light bulbs.
Helium is used in balloons and to cool things.
Xenon is used in headlights for new cars.
Used in the laboratory to help stabilize reactions that would usually proceed too quickly.

55. Noble Gas Stability Atoms want to gain stability
Atoms will try to gain or lose electrons to have a full valence shell
For two atoms to join together atoms must gain, lose or share electrons
Elements with full valence shells do not easily gain or lose electrons

56. Group 3 elements have 3 valence electrons

57. Group 4 elements have 4 valence electrons

58. Group 5 elements have 5 valence electrons

59. Group 6 elements have 6 valence electrons

60. Group 7 (halogens) have 7 valence electrons

61. Halogens
are reactive nonmetallic elements that form strongly acidic compounds with hydrogen, from which simple salts can be made.
The term "halogen" means "salt-former" and compounds containing halogens are called "salts". All halogens have 7 electrons in their outer shells, giving them an oxidation number of -1.

62. Halogens
The halogens exist, at room temperature, in all three states of matter:
Solid- Iodine, Astatine
Liquid- Bromine
Gas- Fluorine, Chlorine

63. Transition metals (“d” block) have 1 or 2 valence electrons

64. Lanthanides and actinides
(“f” block) have 1 or 2 valence electrons

65. Determine the number of shells and the number of valence electrons for:
Carbon - C
2nd Period = 2 shells
4th Group =
4 valence
electrons

66. Determine the number of shells and the number of valence electrons for:
Sodium - Na
3rd Period = 3 shells
1st Group =
1 valence
electron

67. Draw the bohr diagram for the element below.Ne
Name the element.
Number of shells ?
Valence electrons ?

68. Draw the bohr diagram for the element below.Ne
Name the element.
Number of shells ?
Valence electrons ?
Neon
2nd Period = 2 shells
8th Group = 8 valence
electrons

69. Draw the bohr diagram for the element below.
Name the element.
Number of shells ?
Valence electrons ?

70. Draw the bohr diagram for the element below.
Name the element.
Number of shells ?
Valence electrons ?
Hydrogen
1st Period = 1 shell
1st Group = 1 valence
electron

71. Draw the bohr diagram for the element below.
Name the element.
Number of shells ?
Valence electrons ?

72. Draw the bohr diagram for the element below.
Name the element.
Number of shells ?
Valence electrons ?
Beryllium
2nd Period = 2 shells
2nd Group = 2 valence
electrons

73. Draw the bohr diagram for the element below.S
Name the element.
Number of shells ?
Valence electrons ?

74. Draw the bohr diagram for the element below.S
Name the element.
Number of shells ?
Valence electrons ?
Sulfur
3rd Period = 3 shells
6th Group = 6 valence
electrons

75. Draw the bohr diagram for the element below.K
Name the element.
Number of shells ?
Valence electrons ?

76. Draw the bohr diagram for the element below.K
Name the element.
Number of shells ?
Valence electrons ?
Potassium
4th Period = 4 shells
1st Group = 1 valence
electron

77. Draw the bohr diagram for the element below.
Name the element.
Number of shells ?
Valence electrons ?

78. Draw the bohr diagram for the element below.
Name the element.
Number of shells ?
Valence electrons ?
Helium
1st Period = 1 shell
8th Group = 2 valence
electrons
Helium is the exception in Group 8.
Since it has just one shell, that shell can only fit 2 electrons instead of 8.
It is in this group because all the elements have a full outer shell.

79. These diagrams are called Lewis dot symbols.
Look at the Lewis dot symbols and answer the questions.
What is the relationship between the number of dots, the number of valence electrons, and the location of the element?
Create a Lewis dot symbol for fluorine, F. How many bonds do you think fluorine will make?

80. Lewis Dot Notations
An atom’s valence electrons can be represented by Lewis dot notations.
1 valence e- X
2 valence e-
3 valence e-
4 valence e-
5 valence e-
6 valence e-
7 valence e-
8 valence e-

81. Key Questions How do atoms bond to form molecules?
How does one atom bond to another in a molecule?
How do atoms bond to form molecules?

82. You will be able to:
create accurate structural formulas using Lewis dot symbols
describe the type of bonding found in molecular substances
apply the octet rule to predict bonding in molecules
draw Lewis dot structures and structural formulas for molecules that contain double and triple bonds

83. Discussion Notes
Lewis dot symbol: A diagram that uses dots to show the valence electrons of a single atom.
You can use Lewis dot symbols to create Lewis dot structures.
Lewis dot structure: A diagram that uses dots to show the valence electrons of a molecule. This structure shows where the electrons will be shared between atoms

84. Discussion Notes
Octet rule: Nonmetal atoms combine so that each atom has a total of eight valence electrons by sharing electrons.

85. Discussion Notes (cont.)
Some valence electrons are not involved in bonding.
Lone pair: A pair of valence electrons not involved in bonding within a molecule. The two electrons belong to one atom.

86. Discussion Notes (cont.)
A covalent bond is the sharing of a pair of electrons between two nonmetal atoms.
Bonded pair: A pair of electrons that are shared in a covalent bond between two atoms.

87. Wrap Up How does one atom bond to another in a molecule?
A covalent bond is a bond in which two atoms share a pair of valence electrons.
Lewis dot symbols show the valence electrons in an atom and are used to predict bonding in a molecule.

88. Each atom in the molecule has an “octet” of valence electrons
Each atom in the molecule has an “octet” of valence electrons. Note that the hydrogen atoms do not follow the octet rule. They have a total of two electrons, similar to the noble gas helium, He.
After bonding, each chlorine atom has a total of eight valence electrons surrounding it.
Cl2
PCl3
H2S

89. Wrap Up How do atoms bond to form molecules?
Elements form covalent bonds by sharing electrons until each atom has eight valence electrons. This is called the octet rule. Hydrogen is an exception. It forms bonds such that it has two valence electrons.
Atoms can form double and triple bonds to satisfy the octet rule.
When covalent bonds form, each atom resembles a noble gas in its electron configuration.

90. Becoming An Ion Electrons are negatively charged
Protons are positively charged
Neutral atoms do not have a charge because the number of protons is the same as the number of electrons
When atoms gain or lose electrons they become positively or negatively charged
An atom with a charge is called an Ion
Metals try to lose electrons
Non-Metals try to gain electrons

91. Ion
Charged particle that typically results from a loss or gain of electrons
Two types:
Anion = negatively charged particle
Cation = positively charged particle - - - + -
= 8 + + + + - - 9 6 + + - -
Now that three electrons were lost, the number of electrons (6) and protons (8) is still unbalanced; therefore, it is still an ion, but now it is specifically referred to as a cation.
Now that this atom of oxygen just gained an electron, it is no longer neutral or an atom. It is now considered an ion (anion). This ion has more electrons (9) than protons (8).
Currently, this atom of oxygen is neutral because it has an equal number of electrons (8) and protons (8). - -
Symbol = O1-
Symbol = O2+
Symbol = O

92. Atomic Mass
The weighted average of the masses of all the naturally occurring isotopes of an element
The average considers the percent abundance of each isotope in nature
Found on the periodic table of elements
Example
What would be the atomic mass (≈) of Hydrogen if these three isotopes
were found in the following percentages (99.9, 0.015, 0) respectively? - + + + - -
Hydrogen (Protium)
Mass # = 1 amu
Hydrogen (Deuterium)
Mass # = 2 amu
Hydrogen (Tritium)
Mass # = 3 amu
If you simply average the three, 2 amu (1 amu + 2 amu + 3 amu/3) would be the atomic mass, but since 99.9% of the Hydrogen is Protium, the atomic mass is around 1 amu (.999 x 1 amu)