Periodic trends and bonding Review of periodic table and trends Types of bonding Basic naming rules for simple covalent and ionic compounds

Periodic Table Arrangement Period: Horizontal row Group or family: Vertical column Group numbering developed by the International Union of Pure and Applied Chemistry (IUPAC) 1985 Blocks Brown: s-block Brown: s-block Red: p-block Red: p-block Yellow: d-block Yellow: d-block Blue: f-block Blue: f-block

Periodic Trends Atomic radius: distance from nucleus to outermost electron. Trend exists in s- and p- blocks Ionic radius: see above def. Negative ions (anions) have larger radii Negative ions (anions) have larger radii Positive ions (cations) have smaller radii Positive ions (cations) have smaller radii

Periodic Trends Ionization energy: energy required to remove an electron from an atom or ion. Ex: Na + E → Na + + e - Energy unit: kJ/mol Always produces a cation. IE increases across periods and decreases down groups. IE and radius are inversely related. Successive IE supports filled sublevel stability.

Periodic Trends Electron affinity: energy change that occurs when an atom gains an electron. F + e - → F - + E Can be endo- or exothermic. Depends on how an atom’s orbitals are filled. Not as clear of a trend as IE.

Periodic Trends Electronegativity: a measure of how atoms share electrons in a BOND. Important in determining bond polarity. Scale No value for noble gases.

Summing It Up Small radii = electrons held tightly Large radii = electrons held loosely Periodic trends give evidence to orbital theory, electron filling of orbitals and the way matter interacts.

This presentation shows two types of bonding. Ionic bonding Covalent bonding Click on the type of bonding you want to view.

Ionic Bonding Ionic bonds form between metals and non- metals Metal atoms lose electrons to form positive ions Non-metal atoms gain electrons to form negative ions The oppositely charged ions attract one another

Sodium and Chlorine (please draw both) Click to view animation 11+ and 10- = 1+ Na and 18- = 1- Cl - Click for another example + -

Lewis Dot Na Na +1-1 Cl Click to view animation

Magnesium and Oxygen Click for animation 12+ and 10- = 2+ Mg and 10- = 2- O Click for another example

Magnesium and Chlorine Click to view animation 17+ and 18- = 1- Cl and 18- = 1- Cl and 10- = 2+ Mg Click here to return to bonding options

Predicting Charge It’s not always convenient to draw out each atom’s Bohr model. The periodic table can be used to predict the charge on most ions. How?

Using the Periodic Table, predict the charge for the following elements: Magnesium and Fluorine Mg 2+ F - Aluminum and Oxygen Al 3+ O 2- Calcium and Sulfur Calcium and Sulfur Ca 2+ S 2-

Combining Ions Using the Cris-Cross method, write the chemical formula for the ionic compounds from the previous slide (notice how only the numbers get moved, not the charge). Mg 2+ F -  MgF 2 Al 3+ O 2-  Al 2 O 3 Ca 2+ S 2-  CaS

Naming Ionic Compounds Naming is easy! Simply state the name of the metal first Next, state the name of the nonmetal, and change the ending to “ide” Examples: CaCl 2 - Calcium Chloride, MgO - Magnesium Oxide, BeS - Beryllium Sulfide

Special Naming Rules Some metals have more than one possible charge. Ex: Copper can be Cu + or Cu 2+ When naming these ions, consult the “special sheet” and write the roman numeral after the metal to specify. Ex: FeCl 3 – Since Cl is -1, Fe must be +3, so we name this compound: Iron (III) Chloride Iron (III) Chloride

Polyatomic Ions Definition – Ions that are composed of more than one element. NO 3 -, SO 4 2-, NH 4 + (others given on special sheet) When forming a compound w/ Polyatomic ions, place parentheses around them when subscripts conflict with criss-crossing values When naming compounds with polyatomic ions, follow the rules for ionic compounds, but don’t change the ending to “ide”

Practice with Polyatomic Ions Write 3 compounds from the following combinations ions: Li +, Ca 2+, NH 4 +, SO 4 2-, NO 3 -, PO 4 3-

Covalent Bonding Covalent bonds form between non-metal atoms Covalent bonds involve sharing a pair of electrons

Hydrogen and Hydrogen H H2H2 H Click for another example Click for animation

Hydrogen and Hydrogen H H Click to view animation

Nitrogen and Hydrogen (Ammonia) Click for animation Click for another example H H H N NH 3

Hydrogen and Oxygen Click for animation H2OH2O H H O Click here to return to bonding options

Naming Covalent Compounds How they’re different than ionic compounds: Covalent compounds utilize prefixes when naming them. How they’re similar to ionic compounds: The last nonmetal still has “ide” for its ending. 1 – Mono 2 – Di 3 – Tri 4 – Tetra 5 – Penta 6 – Hexa 7 – Hepta 8 – Octa 9 – Nona 10 - Deca

Examples H 2 O – Dihydrogen Monoxide HI – Hydrogen Monoiodide N 2 O 5 – Dinitrogen Pentoxide CCl 4 - Carbon Tetrachloride

Now you try Name or write the formula for the following Compounds: NaF - Ammonium Nitrate NaF - Ammonium Nitrate CH 4 - Nickel (II) Oxide CH 4 - Nickel (II) Oxide Li 2 O - Potassium Carbonate Li 2 O - Potassium Carbonate BH 3 - Copper (I) Phosphate BH 3 - Copper (I) Phosphate SnSO 4 - Sodium Nitride SnSO 4 - Sodium Nitride SF 2 - Calcium Acetate SF 2 - Calcium Acetate FeCl 3 - Lead (IV) Chromate FeCl 3 - Lead (IV) Chromate