Chemical Bonds

Chapter 6

6.1 Ionic Bonding

6.2 Covalent Bonding

Review of what you know

• An electron dot diagram is a model of an atom in which each dot represents a valence electron.

Notice dots for each family/group

Full energy levels

• When the outermost energy level of an atom is filled with electrons, the atom is stable and not likely to react.

• Nobel gases have stable electron configurations with eight valence electrons

Stable or not, Ions come!!

• Elements that do not have complete sets of valence electrons tend to react.

Ionic Bonding

• Some elements achieve stability through the transfer (give away) of electrons between atoms.

Ions Created

• View animation

Formation of Ions 

• Ions are electrically-charged particles formed when atoms lose or gain electrons

• The charge on an ion is represented by a plus or a minus sign.

Cation – ion with a positive charge

Anion – ion with a negative charge

Did it Get or Give an Electron?

Fe+3 Cu+

Give Give

Did it Get or Give an Electron?

Sn+2

Get Give

Br-

Ionization Energy

• An electron can move to a higher energy level when an atom absorbs energy.

• The energy allows electrons to overcome the attraction of the protons in the nucleus.

• The amount of energy used to remove an electron is called ionization energy.

• It varies from element to element. • The lower the ionization energy, the easier

it is to remove an electron from an atom.

Remember Reactivity Demo?

Covalent Bonding

• A chemical bond in which two atoms share a pair of valence electrons.

• When two atoms share one pair of electrons, the bond is called a single bond

More Single Bonds

Molecular Models

•

Double Bond

Double Bond shown in structural formula (not dots!)

What kind of bond?

Triple Bond

Molecule

• A neutral group of atoms that are joined together by one or more covalent bonds.

Chemical Formula

• Used to describe the molecules of an element as well as a compound.

• The element hydrogen has the chemical formula H2.

• The subscript 2 indicates that there are two atoms in a molecule of hydrogen.

F.Y.I.

Exam Question

Most elements are……