Chapter 7: Ionic and Metallic Bonding

Section 2: Ionic Bonds and Ionic Compounds

Formation of Ionic Compounds

• Ionic Compounds– Composed of metal ________ and nonmetal

_____________.• Ex. NaCl → Na+ + Cl-

– Composed of _______, but electrically _____________.

• Total ________ charge = Total _________charge

Formation of Ionic Compounds• Ionic Bond

– Anions and cations attracted by ___________ ______________.

– Example 1• Na _________ electron to Cl• ________ and _______ ions result• Ions are then attracted by their _____________

(+1 and -1)

Formation of Ionic Compounds

• Ionic Bond– Example 2

• Aluminum- _____ valence electrons• Bromine- _____ valence electrons (needs _____)• Aluminum _________ electron to each of three

bromine atoms• ______ ion and ______ ions result

– What is the ionic compound that results?

Formation of Ionic Bonds

• Chemical formula– ________ and _________ of atoms in the

smallest unit of a substance– NaCl, H2O, CH4

• Formula Unit– lowest _________ _________ _______ of

ions in an ionic compound– NaCl – ratio of ___ Na+: ____Cl-

– MgCl2 – ratio of ___ Mg2+ : ____ Cl-

– AlBr3 – ratio of ___ Al3+ : ____ Br-

Formation of Ionic Compounds

AlBr3

Number of Aluminum ions when no number is shown, assume there is 1 ion

Number of Bromide ions

____:____ ratio of Al 3+ ions to Br- ions

PracticePredict the formula units that would form from thefollowing elements1. Draw electron dot structures2. Determine ions that would form3. How many of each ion is needed to have equal +

and – charges?

a. Potassium and iodineb. Potassium and oxygenc. Aluminum and oxygen

Properties of Ionic Compounds

• Solid _________ at room temperature– Ions _________ to their neighbors – strong, ________ structure

• Very ________ melting points– NaCl has a melting point of 800°C

Properties of Ionic Compounds

• Coordination number– number of ions of

_________ _______ that surround an ion

– Coordination # of Na+ : – Coordination # of Cl- :

Practice

What is the coordination number of cesium

in cesium chloride (CsCl)?

Pink- Cs+

Blue- Cl-

Properties of Ionic Compounds• When placed in water

– Crystal structure breaks down, ____ separate– Conduct an _________ __________ when

melted or dissolved

• Electrical current applied to water– ___________ move toward one electrode and

___________ to another– ____________ conducted through the water

by way of ions