Bond Types & Covalent Compounds Mr. Bimber Freedom High School

Naming warm up: 1. NaCl 2. FeO 3. Cu 2 SO 4 4. Tin (IV) Carbonate 5. Ammonium bromide 1. Sodium chloride 2. Iron (II) oxide 3. Copper (I) sulfate 4. Sn(CO 3 ) 2 5. NH 4 Br

Be happy! Were MOOving on to reactions next!

Today you will learn: What every atom wants to be. What every atom wants to be. Three ways they can become what they want. Three ways they can become what they want. How to name atoms that share electrons. How to name atoms that share electrons. How to write formulas for atoms that share. How to write formulas for atoms that share. How to find what the bond is … really. How to find what the bond is … really. How bond type affects compound properties. How bond type affects compound properties.

The Big Picture Since elements are the alphabet of chemistry, compounds are the words. Since elements are the alphabet of chemistry, compounds are the words. Different bonds make different compounds. Different bonds make different compounds. We use different naming rules for different types of compounds. We use different naming rules for different types of compounds.

This is important because: Were almost ready to start speaking sentences in chemistry. In other words…. Were almost ready to start speaking sentences in chemistry. In other words…. Were almost ready to start making stuff happen. Were almost ready to start making stuff happen.

What every atom wants… … to have a full valence (outer) shell of electrons. … to have a full valence (outer) shell of electrons. The Noble Gas elements in family 18 already have a full valence shell. The Noble Gas elements in family 18 already have a full valence shell. Thats why they dont usually react with other elements. Thats why they dont usually react with other elements. Once other elements get a full outer shell, they usually become more stable and less reactive. Once other elements get a full outer shell, they usually become more stable and less reactive.

Three ways atoms get full shells: When metals and nonmetals react: 1. Metals lose outside electrons, so the full shell inside becomes the outside shell. They become positive ions (cations). 2. Nonmetals gain outside electrons. They become negative ions (anions). 3. Two nonmetals can share outside electrons. Neither element gets a charge.

Covalent Compounds Two nonmetals sharing electrons make covalent compounds. Two nonmetals sharing electrons make covalent compounds. There are many different combinations, so the name must say how many of each element are in the compound. There are many different combinations, so the name must say how many of each element are in the compound.

Covalent Names and Formulas: Name the less electronegative element first. (This is usually the element to the left, and/or lower on the Periodic Table.) Name the less electronegative element first. (This is usually the element to the left, and/or lower on the Periodic Table.) The second element gets an -ide ending. The second element gets an -ide ending. Use a prefix to say how many of each element you have, but dont use mono- on the first element. Use a prefix to say how many of each element you have, but dont use mono- on the first element. Examples: carbon dioxide, carbon tetrachloride. Examples: carbon dioxide, carbon tetrachloride.

Covalent Prefixes: Mon(o) = 1 Mon(o) = 1 Di = 2 Di = 2 Tri = 3 Tri = 3 Tetr(a) = 4 Tetr(a) = 4 Pent(a) = 5 Pent(a) = 5 Hex(a)= 6 Hex(a)= 6 (Drop the ending o or a if the element begins with a vowel.)

Covalent Naming Practice: 1. CO 2. SO 2 3. N 2 S 3 4. Phosphorous trichloride 5. Dinitrogen pentoxide 1. Carbon monoxide 2. Sulfur dioxide 3. Dinitrogen trisulfide 4. PCl 3 5. N 2 O 5

Bonds affect compound properties: Ionic compounds usually form crystalline solids that have high melting points and conduct electricity. Most are soluble in water. Ionic compounds usually form crystalline solids that have high melting points and conduct electricity. Most are soluble in water. Covalent compounds can be solid, liquid, or gas. They usually dont conduct electricity. Covalent compounds can be solid, liquid, or gas. They usually dont conduct electricity.

Bond type actually depends on electronegativity difference. –From 0 to 0.4, the bond is mostly covalent (electrons shared evenly). –From 0.4 to 1.0, the bond is slightly polar (uneven electron sharing). –From 1.0 to 2.0, the bond is strongly polar. –Above 2.0, the bond is ionic (one atom takes electrons from the other.) This is too complicated for naming purposes, so… This is too complicated for naming purposes, so… Just use the stair steps to choose which naming rules to follow. Just use the stair steps to choose which naming rules to follow.

Traps and Tips First decide which naming rules to use. First decide which naming rules to use. Multiple charges? Multiple charges? Polyatomic ions? Polyatomic ions? Prefixes? Prefixes? Only nonmetals make covalent compounds. Only nonmetals make covalent compounds. Naming is decided by the stair steps. Naming is decided by the stair steps. Electronegativity difference is more accurate. Electronegativity difference is more accurate.

Summary All atoms want a full valence shell. All atoms want a full valence shell. They do this by gaining, losing, or sharing their outside electrons. They do this by gaining, losing, or sharing their outside electrons. –Metals lose, become cations. –Nonmetals gain from metals, become anions. –Nonmetals with nonmetals can share electrons. Covalent and ionic compounds have different: Covalent and ionic compounds have different: –Naming rules –Compound properties.

Get it? Name prefixes Name prefixes one to six: one to six: N 2 O 4 N 2 O 4 ionic compound properties: ionic compound properties: Mono, di, tri Mono, di, tri tetra, penta, hexa Dinitrogen tetroxide Dinitrogen tetroxide Water soluble solid, Water soluble solid, high melting temperature, conduct electricity conduct electricity