Module 6 Lesson 1 Ion Formation

Module 6:Lesson 1 Ion Formation

Focus Question

Why do elements form compounds?

New Vocabulary

chemical bond

cation

anion

Review Vocabulary

octet rule: atoms tend to gain, lose, or share
electrons in order to acquire eight valence
electrons

Valence Electrons and Chemical Bonds

• A chemical bond is the force that holds two

atoms together.

• Chemical bonds can form by the attraction

between the positive nucleus of one atom
and the negative electrons of another atom,
or by the attraction between positive ions and
negative ions.

Valence Electrons and Chemical Bonds

• Electron-dot structures can be used to

illustrate the formation of chemical bonds.

Valence Electrons and Chemical Bonds

• Ionization energy refers to how easily an atom

loses an electron.

• Electron affinity indicates how much

attraction an atom has for electrons.

• Noble gases, which have high ionization

energies and low electron affinities, show a
general lack of chemical reactivity.

• Noble gases have electron configurations with

a full outermost energy level.

Valence Electrons and Chemical Bonds

• Elements tend to react to acquire the stable

electron structure of a noble gas.

• Atoms try to form an octet—a stable

arrangement of eight valence electrons in the
outer energy level—by gaining or losing
valence electrons.

Positive Ion Formation

• A positive ion forms when an atom loses one

or more valence electrons in order to attain a
noble gas configuration.

• A positively charged ion is called a cation.

Multiple Choice

A(n) ______________is an ion that has a positive charge.

• anion

• cation

• isotope

• allotrope

Positive Ion Formation

• This figure illustrates

how sodium loses a
valence electron to
become a sodium
cation.

• By losing an

electron, the sodium
atom acquires the
stable outer electron
configuration of
neon.

Positive Ion Formation

• Metals atoms are reactive because they lose

valence electrons easily. Group 1 and 2 metals
are the most reactive metals.

• The ions formed by metal atoms in groups 1,

2, and 13 are summarized below.

Multiple Choice

What is the electron configuration of the sodium atom after it loses an electron?

• 1s²2s²2p⁶3s¹

• 1s²2s²2p⁶3s²

• [He]2s²2p⁵

• 1s²2s²2p⁶

Multiple Choice

What is the electron configuration of the chlorine atom after it gains an electron?

• 1s²2s²2p⁶3s²3p⁵

• 1s²2s²2p⁶3s²3p⁶4s¹

• 1s²2s²2p⁶3s²3p⁶

• 1s²2s²2p⁶

Multiple Choice

Why is the calcium ion (Ca²⁺) more stable than the calcium atom (Ca)?

• The noble gas configuration is more stable.

• Twenty electrons are more stable than eighteen electrons.

• Eighteen electrons are less stable than twenty electrons.

• The two electrons more than the noble gas configuration is more stable.

Positive Ion Formation

• Transition metals commonly form 2+ or 3+

ions, but can also form ions of 3+ or greater.

• Other relatively stable electron arrangements

are called pseudo-noble gas configurations.

Multiple Choice

Which is NOT true of the Sc³⁺ ion?

• It is a scandium ion with three positive charges.

• It is considered to be a different element than a neutral Sc atom.

• 
  It has the same electron configuration as Ar.

• 
  It was formed by the loss of 4s and 3d electrons.

Multiple Choice

Explain why the Zn²⁺ ion has some stability.

• The zinc ion is a transition metal.

• The zinc ion has bonded with two free electrons.

• The zinc ion has achieved a noble gas configuration.

• The zinc ion has full s, p, and d sublevels to form a pseudo-noble gas configuration.

Negative Ion Formation

• Nonmetals easily gain

electrons to attain a
stable outer electron
configuration.

• The figure shows

chlorine gaining an
electron.

• An anion is a negatively

charged ion. Thus, the
chlorine atom becomes
a chloride anion.

Multiple Choice

A(n) is an ion that has a negative charge

• anion

• cation

• isotope

• allotrope

Negative Ion Formation

• As shown in the table, nonmetal ions gain

the number of electrons required to fill an
octet and gain a noble-gas configuration.

• Some nonmetals can gain or lose other

numbers of electrons to complete an octet.

Multiple Choice

What is the electron configuration of the neutral fluorine atom?

• 1s²2s²2p⁵

• 1s²2s²2p⁶

• 1s²2s²2p³

• 1s²2s²2p⁸

Multiple Choice

Explain how an anion of nitrogen forms.

• nitrogen loses 3 electrons

• nitrogen gains 3 electrons

• nitrogen gains 3 protons

• nitrogen loses 3 protons

Multiple Choice

The orbital notation of sulfur is shown below. Explain how sulfur forms its ion.

• sulfur will gain 2 electrons in the 3p sublevel.

• sulfur will gain 3 electrons in the 3p sublevel.

• sulfur will lose 4 electrons in the 3p sublevel.

• sulfur will lose 2 electrons in the 3p sublevel.