For Test #6: The Periodic Table

The Periodic Table

1) Dimitri Mendeleev – 1st to publish a periodic table.

2) The Periodic Law: When arranged by increasing atomic number, the elements display a regular and repeating pattern of chemical and physical properties.

Groups vs Periods

• Groups – contain elements with similar chemical properties (vertical columns) because they all have the same number of valence (outer shell) electrons.

• Periods – contains elements with the same number of occupied energy levels. Their chemical properties vary.

• Note: Know special group names

Can YOU name the special groups?

Reading the Periodic Table: Classification

• Nonmetals, Metals, Metalloids, Noble gases

Classes of Elements

Phases of Elements

Most Reactive Metal

Most reactive nonmetal

Liquids

Gases

1) Which is the more reactive metal? A) Potassium or cesium? B) Calcium or barium?2) Which is the more reactive nonmetal? A) Iodine or Chlorine? B) Carbon or Oxygen?

Reading the Periodic Table: Classification

• Nonmetals, Metals, Metalloids, Noble gases

Can you name the symbols for the gases?

Reading the Periodic Table: Classification

• Nonmetals, Metals, Metalloids, Noble gases

Can you name the metalloids?

Reading the Periodic Table: Classification

• Nonmetals, Metals, Metalloids, Noble gases

Can you name the 2 liquid elements?

Atomic Radius• Atomic Radius is the distance from the center of an

atom to its outermost electron shell.• Values on Table S• Units are picometers (pm)

1) Atomic Radius increases as you move down a group because there are more shells of electrons.

2) Atomic Radius decreases as you move to the right across a period because the nuclear charge increases & pulls the electrons in closer to the nucleus. http://www.youtube.com/watch?v=ba2yN2HtPTA&feature=related

Atomic Radius Trends

Bigger

Smaller

Ionization Energy

• Ionization energy is the amount of energy needed to pull an electron from an gaseous atom.

• Values on Table S• Units are kilojoules per mole (kJ/mol)• It takes more energy to pull electrons off smaller

atoms.• Trends are opposite of that for atomic radius.

Ionization Energy Trends1) Ionization Energy decreases as you move down a group.

2) Ionization Energy increases as you move to the right across a period.

Bigger

Smaller

Ionization Energy Trends

Electronegativity• Electronegativity measures how much an atom

attracts shared electrons in a chemical bond (“electron attraction”)

• Linus Pauling – created the electronegativity scale with fluorine having the largest attraction for electrons and it is assigned the biggest value of 4.0

• Values on Table S (no units)

Electronegativity Trends

• Same as ionization energy• Reason: If it takes a lot of energy to remove an

electron, the atom must have a big attraction for the electron.

Bigger

Smaller

Summary

Atomic Radius decreasesNuclear Charge increasesElectronegativity increasesIonization Energy increases

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Octet Rule1. Atoms will gain, lose, or share valence electrons with

other atoms in order to obtain an octet (8 valence electrons).

2. Hydrogen & Helium are the only exceptions – they want 2 valence electrons.

3. Recall: Atoms are neutral. Why? _________________4. An ion is the charged particle formed when neutral

atoms lose or gain electrons.5. If an atom gains electrons, it becomes a ____________

charged ion.6. If an atom loses electrons, it becomes a ____________

charged ion.

Metal Ions

• Metal tends to give up electrons and form smaller sized ions that are positively charged.

Atom Ion

Nonmetal Ions

• Nonmetals tend to gain electrons and form larger sized ions that are negatively charged.

Atom Ion

Why?

1. Metals generally have 1, 2, or 3 valence electrons. For metals it is easier to lose those than gain 5,6,or 7 additional electrons.

2. Nonmetals generally have 5, 6, or 7 valence electrons. For nonmetals it is easier to gain 1, 2, or 3 more electrons than to lose 5, 6, or 7 electrons.

Allotropes

Diatomic vs Monoatomic Elements

Don’t Forget

1)How to find #p, #e, #n2)Ground State vs Excited State3)Special Group Names4)Isotopes