Ionic Bonding Naming and formula writing Mrs. Kay & Ms. Cleary Chemistry 11 Read pages

Recall Atoms of different elements have different numbers of electrons Each shell is filled up before electrons move to the next shell found further away from the nucleus Ex: Sodium has 2 e- on the 1 st energy level, 8 e- on the 2 nd energy level, and 1 e- on the 3 rd energy level. Sodium has 1 valence electron

Valence electrons Period number indicates the number of electron shells Period number indicates the number of electron shells Group number indicates the number of valence electrons (look at the second digit of the group number) Group number indicates the number of valence electrons (look at the second digit of the group number)

Trends: Elements of the same group have similar chemical properties because they have the same number of electrons in their outer shell or valence shell Group 1 metals reacting with water

Reasons for reactions Group 18, the noble gases are the most stable of elements because their valence shell is full with electrons Group 18, the noble gases are the most stable of elements because their valence shell is full with electrons Less energy required to support the atom Less energy required to support the atom Other atoms react in attempt to achieve nobel gas configuration, same number of valence electrons as a noble gas. Other atoms react in attempt to achieve nobel gas configuration, same number of valence electrons as a noble gas.

Lewis Dot structures Visual representation of an element and only its valence electrons Visual representation of an element and only its valence electrons sodium, Na has 1 valence so it has 1 dot representing that electron. (group 1) sodium, Na has 1 valence so it has 1 dot representing that electron. (group 1) Chlorine, Cl has 7 electrons. (group 17) Chlorine, Cl has 7 electrons. (group 17) Electrons get placed up along 4 sides of the element before they double up! Electrons get placed up along 4 sides of the element before they double up!

Ionic Bonding attraction between oppositely charged ions formed when metallic ions (+) transfer electron(s) to nonmetallic ions (-) attraction between oppositely charged ions formed when metallic ions (+) transfer electron(s) to nonmetallic ions (-) Difference of electronegativity greater than 1.7 Difference of electronegativity greater than 1.7 Ex: NaCl Ex: NaCl

Not always 1:1 ratio, sometimes need to use subscript to show the number of atoms Ex: CaCl 2 The 2 is a subscript, it shows that 2 atoms of chlorine bond with one atom of calcium. Zero Sum Rule: the charges need to add up to zero

Naming Ionic Compounds

Simple or Binary Ionic Compounds (Formula to Name) KBr KBr Name the (cation) metal first Name the (cation) metal first Potassium Potassium Name the root of the (anion) non-metal, change the (suffix) end to –ide Name the root of the (anion) non-metal, change the (suffix) end to –ide Bromine becomes bromide Bromine becomes bromide Put together: Potassium bromide Put together: Potassium bromide

Practice Na 2 O Na 2 O Name the metal: Sodium Name the non-metal: Oxide Put them together to get: Sodium Oxide. It takes two Na + to combine with one O 2- to observe the Zero Sum Rule!

Simple or Binary Ionic Compounds (Name to Formula) To write the formula from a name first you must look at the charges. To write the formula from a name first you must look at the charges. Remember ionic compounds are made up of cations and anions (oppositly charged ions) but together the compound has no charge- the charges balance each other out. Remember ionic compounds are made up of cations and anions (oppositly charged ions) but together the compound has no charge- the charges balance each other out.

“Cross-over Method” This is a method used to make sure your compound is balanced. This is a method used to make sure your compound is balanced. Write the formulas of the ions beside each other, then cross the number of the charge of the cation so that it becomes the subscript of the anion. Then cross over the number of the charge on the anion so that it becomes the subscript of the cation. Write the formulas of the ions beside each other, then cross the number of the charge of the cation so that it becomes the subscript of the anion. Then cross over the number of the charge on the anion so that it becomes the subscript of the cation. Mg 2+ Cl 1- MgCl 2

Simple or Binary Ionic Compounds (Name to Formula) If you’re given the name, can you write the formula? If you’re given the name, can you write the formula? Strontium nitride Strontium nitride Strontium is Sr 2+ Strontium is Sr 2+ Nitride is N 3- Nitride is N 3- We must combine them to be equal to zero We must combine them to be equal to zero Need 3 Sr 2+ to combine with 2 N 3- Need 3 Sr 2+ to combine with 2 N 3- Answer is Sr 3 N 2 Answer is Sr 3 N 2

Multivalent Ionic bonding Whenever the periodic table of ions has a split cell, we must choose or indicate which charge we are referring to in the chemical equation. Whenever the periodic table of ions has a split cell, we must choose or indicate which charge we are referring to in the chemical equation. Look at Iron, the charge on Fe is written as a roman numeral between the cation and the anion. Look at Iron, the charge on Fe is written as a roman numeral between the cation and the anion. There is an option of Fe 2+ and Fe 3+ There is an option of Fe 2+ and Fe 3+ FeO would be called Iron (II) oxide FeO would be called Iron (II) oxide It takes Fe 2+ to balance out charges with O 2- It takes Fe 2+ to balance out charges with O 2- We indicate the optional charge with roman numerals; 2= II, 3=III, 4=IV and so on We indicate the optional charge with roman numerals; 2= II, 3=III, 4=IV and so on

Practice naming 1. FeCl 2 2. MnO 3. Fe 2 O 3 4. TiO 2 1. Iron (II) chloride 2.Manganese (II) oxide 3.Iron (III) oxide 4.Titanium (IV) oxide

Polyatomic ions Ions that are made of multiple atoms covalently bonded together. Ions that are made of multiple atoms covalently bonded together. We treat them like a unit or package We treat them like a unit or package When we need more than one, must be put in brackets!! When we need more than one, must be put in brackets!! Example: sulphate, SO 4 2- Example: sulphate, SO 4 2- Aluminum sulphate = Al 2 (SO 4 ) 3 Aluminum sulphate = Al 2 (SO 4 ) 3 Because is Al 3+ and SO 4 2- must combine to Zero Because is Al 3+ and SO 4 2- must combine to Zero

Practice 1. NaOH 2. K 3 PO 4 3. CsMnO 4 4. Ca(HCO 3 ) 2 5. Cu(NO 3 ) 2 1.Sodium hydroxide 2.Potassium phosphate 3.Cesium permanganate 4.Calcium hydrogen carbonate 5.Copper (II) nitrate

Homework: 1. Don’t forget to read over the textbook pages for furhter understanding 2. Work on handouts to continue practice with naming and proper formula writing (IUPAC = international naming method, what we learned)

Test what you know here: du/svb/tutorial/namingc sn7.html du/svb/tutorial/namingc sn7.html du/svb/tutorial/namingc sn7.html