&

Bell Work Write the Electron Configuration and Circle

the Valence Electrons for:

Magnesium

Calcium

Learning Check

A. X would be the electron dot formula for

1) Mg 2) K 3) Al

B. X would be the electron dot formula

1) C 2) N 3) P

Objectives:

• Relate electron configurations to chemical reactivity (chemical bonds).

• Determine valence electrons.

Atom – the smallest unit of matter “indivisible”

Heliumatom

Review

a) Atomic number = number of Electrons

b) Electrons vary in the amount of energy they possess, and they occur at certain energy levels or electron shells.

c) Electron shells determine how an atom behaves when it encounters other atoms

d) Valence electrons -the electrons in the outermost shell of the atom.

Review

Why are some elements reactive and others are not?

• Reactivity depends upon the electron configuration of its atom (valence electrons).

• Noble gases are the least reactive (because of their full outer energy levels).

• Alkali metals and halogens are the most reactive (because they can gain or lose electrons to form a stable noble gas configuration).

Octet Rule = atoms tend to gain, lose or share electrons so as to have 8 electrons

C would like to N would like toO would like to

Gain 4 electronsGain 3 electronsGain 2 electrons

Why are electrons important?

1)Elements have different electron configurations

2)Different electron configurations mean different levels of bonding

Remember:

• An atom or molecule that has gained or lost one or more electrons and has a positive or negative charge.

What are Cations?

• An atom that has lost an electron (s) to become a positive ion.

11p+ 12n°

11p+ 12n°

Na Atom

Loses an electron

Na Ion

What are anions?

• An atom that has gained an electron (s) to become a negative ion.

Do metals and nonmetals form ions differently?

• Nearly all metals from cations.

• The atoms of nonmetals form anions.

What is an Ionic Bond?

• Bond Between an Anion and Cation

• Electrons Are Transferred.

IONIC BONDbond formed between

two ions by the transfer of electrons

Ionic BondingSodium Atom loses an electron to become a Sodium cation with a +1 charge.

loses and electron

Chlorine Atom gains an electron to become a Chlorine cation with a -1 charge.

gains and electron

17- e 18- e

Na Na +11+ P 11+ P

11- e10- e

Cl Cl -

17+ P 17+ P

Homework

• Chemistry/Chapter 7.1 Assessment

• Honors Chemistr/Page 232; 46-59