Ionic Compounds Whats a chemical bond A chemical

Ionic Compounds

What’s a chemical bond? A chemical bond is the force that holds two atoms together n Two types of chemical bonds: n – Ionic – Covalent

Why do atoms form bonds? Formation of chemical bonds is due to number of valence electrons n Why do valence electrons play such an important role? n – Because elements react to get the stable electron structure of a noble gas How many electrons do atoms want to have in their outermost energy level? 8

The Octet Rule States that atoms lose, gain or share electrons in order to acquire a full set of eight valence electrons n Why? This is the stable electron configuration of the noble gases n How do we know if they will gain or lose electrons? Atoms will do what is easiest to get the most stable electron configuration. Atoms with 1, 2 or 3 valence electrons will lose ______ electrons. Atoms with 5, 6 or 7 valence electrons will gain ______ electrons.

How do atoms form bonds? n One way is by the formation of ions. n An ion is an atom (or a group of bonded atoms) with a positive or negative charge. - Proton - Neutron - Electron Sodium Atom What would be the easiest way this sodium atom could get the perfect 8? Sodium Ion

Positive or Negative Ion? n How can you tell if the ion formed will be positive or negative? – Count the protons and electrons 11 How many protons? ___ How many protons? 11 ___ 11 How many electrons? ___ 0 What’s the charge? ___ 10 How many electrons? ___ What’s the charge? +1 ___

Activity Time n Obtain an ion card from teacher n If you have a metal ion, go to the back of the room n If you have a nonmetal ion, go to the front of the room n Once there, look at the other members of your group and start generating conclusions

Conclusions from Activity n What type of atoms form positive ions? – Metals n What type of atoms form negative ions? – Nonmetals

Let’s Go Further n If you have an alkali metal, stand near the fire extinguisher n If you have an alkaline earth metal, stand by the fume hood n If you have a transition metal, go to the front middle lab table n If you have a halogen, stand near the computer n Any others? Stand by my desk

What did we learn? +1 All alkali metals have a charge of _____. +2 n All alkaline earth metals have a charge of _____. -1 n All halogens have a charge of ____. -2 n Group 6 A elements have a charge of ____. n

Transition Elements n How many valence electrons do transition elements have? – Two They will commonly lose those two valence electrons to form ions with a +2 charge n But…. they can also lose some of their d electrons to form ions of +3, +4 or greater n

Roman Numerals n System used to indicate numbers – – n I=1 II = 2 III = 3 IV = 4 We use Roman Numerals to indicate charge of transition metals – Copper (II) = Copper +2 – Iron (III) = Iron +3

Names of Ions n A positively charged ion is called a cation. – A cation’s name is the same as the element n A negatively charge ion is called an anion. – An anion’s name has the ending “–ide” added to the root name § Example: Anion of chlorine is the chloride ion. 1. What is the oxygen ion oxide called? 2. What is the fluorine ion called? fluoride 3. What is the bromine ion called? bromide

Practice Questions 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. Which type of atoms form cations? metals Which type of atoms form anions? nonmetals Is Na+ a cation or anion? cation Is F- a cation of anion? anion Is Ca 2+ a cation or anion? cation Is Mg 2+ a cation or anion? cation What is the charge of the iodine ion? -1 What is the name of the iodine anion? iodide Would oxygen form a cation or anion? anion What is the net charge of zinc (II)? 2+

Monatomic vs. Polyatomic Mono means one n Poly means many n So, a monatomic ion refers to ions with single atoms n A polyatomic ion refers to ions with more than one atom n

Monatomic Ions n Elements as they are on the periodic table form monatomic ions

Polyatomic Ions § Formed when more than one atom are grouped together § Charge on polyatomic ions applies to entire group of atoms. § The polyatomic ion acts as an individual ion Common Polyatomic Ions Sulfate Carbonate NH 4+ Ammonium NO 3 - Nitrate OH- Hydroxide CO 32 - Carbonate SO 42 - Sulfate PO 43 - Phosphate NO 2 - Nitrite