Periodic Table – Let’s Sum it Up.

COLUMNSCOLUMNS = FAMILIESFAMILIES ROWS = PERIODS How many periods are there in the table? How many groups or families are present?

Bohr’s Atomic Model The electrons of an element’s atom fill different energy levels, starting with the first energy level.

Elements in the same period are similar in that their last electrons are in the same energy level. Period 1 Period 2 Period 3 Period 4

Elements in the s and p block follow fairly typical trends. They are called the MAIN GROUP ELEMENTS. CIRCLE THEM.

Placement of the f-block

Main Group Elements For the main group elements (not including transition metals) we can observer periodic trends. – Valence electrons – Ion Charge – Atomic Radius – Ionic Radius – Ionization Energy – Electronegativity

Similarities in Properties Elements in group 17 are called __________________________ Why are they in a group together? (2 reasons)

Atomic Radius

Atomic Radius – what do you expect to happen? SHIELDING EFFECT – inner energy electrons block the nuclear pull on the outer energy electrons. As we go down a family from top to bottom, the principle energy level increases. So, the atomic radius should also _________________________.

Atomic Radius – HOWEVER… As we go across a period, the electrons remain in the same principal energy cloud, but the number of protons increases. So there is a stronger NUCLEAR CHARGE. So, as we go across a period, the atomic radius _________________________ from left to right.

Trends in Atomic Size 6.3 Size generally ____________________ across a period. Size generally ____________________ down a group period.

Valence Electrons Octet Rule: atoms are typically very stable when they have a full valence shell of 8 electrons. Atoms will lose or gain electrons to complete the octet. – Why are the noble gases so stable? – What will alkali metals do to become stable? – What will alkaline earth metals do to become stable? – What will halogens do to become stable? – What will chalcogens do to become stable? – What about noble gases?

Ionic Radius - prediction If an atom loses an electron and becomes a _______________, the size of the ion should be _______________ than the original atom. Why? But, if an atom gains an electron and becomes an __________, the size should be ____________ than the original atom. Why?

What type of elements form cations that are smaller? 6.3

What type of elements form anions that are bigger? 6.3

First Ionization Energy The energy required to remove the outermost electron from an atom. SHIELDING EFFECT - the inner energy level electrons in an atom block the nuclear pull on the outer electrons. Which element do you think will have the lowest ionization energy? (The one who gives it up the easiest.) Li Na K Rb Cs

______________________ across periods _____________________ down a group

Some other loose ends… Diatomic elements Exceptions to anticipated electron configurations Tour of the Periodic Table Trends-in-the-Periodic-Table.htm Trends-in-the-Periodic-Table.htm

Diatomic Molecules When 2 atoms of the same element share electrons and are chemically bonded Examples existing in nature: – Cl 2 I 2 F 2 Br 2 O 2 H 2 N 2 All gases except for Bromine (liquid) Where are they on the periodic table? Based on what we know about periodicity and valence electrons why might they combine?

Electron Configuration Exceptions List the elements written on the board. Draw an orbital diagram for the outer most electrons. Explain why these don’t follow convention.