1. Properties of Atoms and the Periodic Table
Chapter 17
Pages

2. Section 1: Structure of the Atom

3. What is an atom??? First, let’s review what an element is:
An element is matter that is composed ONLY of one type of atom.
An atom is the smallest piece of matter that still retains the properties of the element.
Example: The element oxygen is composed of only oxygen atoms.

4. Composition of Atoms Atoms are composed of 3 general particles:
Charge
Location
Proton
Positive (+)
Nucleus
Neutron
No charge (neutral)
Electron
Negative (-)
Outside the Nucleus

5. How are atoms of the various elements different???
Atoms of different elements contain DIFFERENT NUMBERS OF PROTONS!!!

6. Quarks
Quarks are very small particles that make up both protons and neutrons!
At this time, scientists do not think that electrons can be broken down into smaller pieces.

8. Finding Quarks
To study quarks, charged particles are accelerated (almost to the speed of light) and forced to collide with a proton. The collision causes the proton to break apart.
The Large Hadron Collider, located in Switzerland and France, consists of a circular tunnel with a circumference of 17 miles!

9. Finding Quarks

10. The Changing Atomic Model
400 BC: Democritus proposed the idea that atoms make up all substances.
Aristotle said matter was uniform throughout and was not composed of smaller particles.
1800’s: John Dalton proved atoms exist.

11. The Electron Cloud Model
An electron cloud is the area around the nucleus of an atom where the electrons are most likely to be found.
The electron cloud is
100,000 times larger
than the diameter of
the nucleus.
Electrons are MUCH
smaller than protons.

12. Atomic Model Example
Example: We want to build a model of a hydrogen atom. We will represent the nucleus with a marble that has a radius of 2.4 cm.
Any guesses as to how big we need to make the entire atom???
1.2 kilometers!!!!!!!

13. Section 2: Masses of Atoms

14. Atomic Mass
Protons and Neutrons have about the same mass (1.67 x 10-24g)……VERY small
Both protons and neutrons have 1,836 times more mass than an electron.
Atomic Mass Unit (AMU) is the measurement used for the mass of a proton or neutron.

15. What element is it? You need to know how many protons it has!
The number of protons in an atom is equal to the atomic number.

16. Mass Number
The mass number of an atom is the sum of the number of protons AND the number of neutrons in the nucleus.

17. So how do you find the number of Neutrons???
mass # - atomic #

18. Lets Do an Example Element: Strontium, (#38) Atomic Number: 38
Mass Number: 88
Number Protons: 38
Number Neutrons: 50
Number Electrons: 38

19. Carbon Dating…What is it???
Carbon dating uses isotopes of carbon that are radioactive and have a half-life to date once living organisms.

20. Wrong King of Carbon Dating
This is NOT carbon dating.

21. Isotopes
Isotopes are atoms of the same element with different numbers of NEUTRONS!!!!

22. Identifying Isotopes
To identify each isotope, write the mass number of the isotope behind the element name:
Boron-10
Boron-11
The average atomic mass is the weighted –average mass of the mixtures of it’s isotopes.

24. Isotope Example Chromium-58 Chromium-63 # Protons: _____
# Neutrons: _____
# Electrons: _____
Chromium-63

25. Section 3: The Periodic Table

26. Organizing the Elements
Late 1800’s Dmitri Mendeleev, Russian chemist
Ordered elements by increasing atomic masses.
Left blank spaces in the table to keep the elements
lined up.
He predicted the
properties of
elements not yet
discovered! (and
was accurate!)

27. Organizing the Periodic Table
The vertical columns are labeled 1-18 and are called groups.
The horizontal columns are labeled1-7 and are called periods
Elements in each group have similar properties

28. Electron Cloud Structure
Electrons are located outside of the nucleus of an atom…but do we know exactly where?
Electrons have different amounts of energy, and exist in different energy levels within the atom.

29. Continued…electron cloud structure
The closest electrons to the nucleus have the lowest amounts of energy, where the farthest electrons away from the nucleus have the most energy.
Elements in the
same group have the
same number of
electrons in their
outer energy level.

30. Implications of Electron Cloud Structure
The number of electrons in the outer energy level determines the chemical properties of that element.
Electrons in the outer
energy level also called
Valence Electrons.

31. Electron Dot Diagrams
Electron dot diagrams use the symbol of the element and dots to represent the electrons in the outer energy level.
Also can be called
Lewis Structures.

32. Bohr Structures
Bohr Model- includes all electrons.

33. Elements in the UniverseZ
Element
Parts per million 1
Hydrogen
739,000 2
Helium
240,000 8
Oxygen
10,400 6
Carbon
4,600 10
Neon
1,340 26
Iron
1,090 7
Nitrogen
960 14
Silicon
650 12
Magnesium
580 16
Sulfur
440

34. Elements and Their Properties
Chapter 19 Pg

35. Section 1: Metals

36. Properties of Metals 1. Good conductors of heat and electricity
2. All but mercury are solid at room temperature.

37. More Properties of Metals
3. Metals reflect light. This property is called luster

38. More Properties of Metals
4. Metals are malleable- they can be hammered or rolled into sheets.
5. Metals are ductile- they can be drawn into wires.

39. Ionic Bonding in Metals
Metals usually have 1-3 electrons in their outer energy levels.
Metals can “give” one or more of their outer electrons to another atom, thus bonding them together by sharing electron(s).

40. Metallic Bonding
Metallic bonding-electrons in outer energy level are shared between all the atoms.

41. Alkali Metals Group 1 Softer than most metals
Most reactive of all the metals especially with air and water.
Do not exist in the earth in their elemental form, so they are stored in substances that are not reactive, like oil.
Group 1 Alkali metals have
1 electron in their outer shell,
And combine easily with group
17 elements.

42. Alkaline Earth Metals Group 2 of the Periodic Table
Each atom of this group has 2 valence electrons.

43. Alkaline Earth Metals- Uses
Fireworks! Magnesium makes a white explosion, and strontium produce red.
Magnesium used in making cars, planes, and spacecraft.
Our bones need calcium to keep them strong.

44. Transition Elements Found in groups 3-12 in the Periodic Table
Often form colored compounds. Example gems (chromium), some paints made from compounds of cobalt and/or cadmium.

45. Iron, Cobalt and Nickel
All three elements are used to make steel, with iron making up most of steel.
Nickel is added to give extra strength and to give a shiny, protective coating.

46. Copper, Silver and Gold Group 11
Called “coinage metals” because they were once used to make coins.
(now most coins are made of nickel and copper!)
Copper used in electrical wiring
Compounds containing silver help with making photographs appear on paper.
Silver and gold used in jewelry.

47. Zinc, Cadmium, and Mercury
Group 12
Cadmium is used in rechargeable batteries
Mercury- the only metal that is a liquid at room temperature. Used in thermometers, thermostats, and batteries.
Mercury is VERY poisonous!!!

48. The Inner Transition Metals
Lanthanides and Actinides.
Lanthanides #’s 58-71, named because they follow the element Lanthanum (#57)
Actinides #’s , named because they follow the element Actinium (#89)
All actinides are radioactive and unstable!
Ex: Uranium used for nuclear energy.

49. Metals in the Earth’s Crust
Metals are mined and then separated from other rock.
Most platinum is located in
South Africa.

50. Ores: Minerals and Mixtures
Ore: made of a metal compound, or mineral, within a mixture of clay and/or rock.
Process:
Separate rock from mineral.
Roasting- mineral converted to another physical form-uses heat
Metal refined into pure form.

51. Section 2: Nonmetals

52. Properties of Nonmetals
Nonmetals are usually gases or brittle solids at room temperature.
Nonmetals are not malleable or ductile. They do not conduct heat or electricity, they are not shiny.
Nonmetals are found to the right side of the periodic table (plus Hydrogen)

53. Elements in the Human Body

54. Bonding in Nonmetals Nonmetals can form ionic and covalent compounds.
Examples: textbook pg. 579
Pb S = PbS

55. Hydrogen
Hydrogen in it’s gas form is a diatomic molecule: it consists of two atoms of the same element held together with a covalent bond.
Example: H2
Hydrogen is VERY reactive. It has one electron and can combine with other elements to share the electron.

56. Halogens Group 17, includes F, Cl, Br, I, and At
Seven valence electrons in outer energy level.

58. Uses of Halogens Chlorine is used to disinfect pool water.
Iodine is a solid at room temperature and when heated changes directly to a gas: the process of sublimation!

59. The Noble Gases
Stable because they have full outer energy levels.

60. Section 3: Mixed Groups

61. Properties of Metalliods
Metalloids share properties of both metals and nonmetals.
Metalliods also called
SEMICONDUCTORS
because they can
conduct electricity
better than nonmetals,
but not as well as metals.

62. The Boron Group
Group 13
Boron is a metalliod. Household items that contain compounds of boron are borax (used in laundry detergent) and boric acid (insecticide).
Aluminum is the most abundant
metal in earth’s crust,
and is used in soft-drink
cans, foil wrap,
and to construct airplanes.

63. The Carbon Group Each element in group 14 has 4 valence electrons.
Carbon is a nonmetal
and is found in coal, oil,
natural gas, and foods.
Plants use carbon
dioxide and sunlight
to make glucose.

64. Continued…The Carbon Group
Allotropes are different forms of the same element.
Example: Carbon: Diamond and Graphite

65. Semiconductors
Silicon is the main component in semiconductors, Germanium is also used
Semiconductors: (elements that conduct an electric current under certain conditions).
Tin used to coat other metals to prevent corrosion.
Lead was once used in paints,
but is no longer because
it is toxic!

66. The Nitrogen Group Group 15- Each element has 5 valence electrons.
Nitrogen makes up 80% of the air we breathe, and is the 4th most abundant element in our bodies.
Bismuth and Antimony are metals that are used in fire-sprinkler
heads because they help
to lower the melting points.

67. The Oxygen Group
Group 16,
Oxygen used by all living things to breathe.
Sulfur compounds used for pigments in paints.
Selenium needed in the body in VERY small amounts, too much is toxic.
Also used to make photocopies.

68. Synthetic Elements
Scientists create elements by smashing existing elements in a particle accelerator.
Example: Smashing uranium with neutrons can make neptunium.
Neptunium atoms only last for about 2 days, and when they disintegrate, they form plutonium.

69. Transuranium Elements
Elements with more than 92 protons.
They are synthetic, unstable, and many of them disintegrate quickly.