Chemical Bonds forces that attract atoms to each other to form compounds involves the interactions of valence electrons between atoms usually the bond forms a compound that is more stable than the atoms individually.

Properties of Ionic and Covalent Compounds

IONIC BOND bond formed between two ions by the transfer of electrons

COVALENT BOND bond formed by the sharing of electrons

Formation of Ions from Metals Ionic compounds result when metals react with nonmetals Metals lose electrons to match the number of valence electrons of their nearest noble gas Positive ions (cations) form when the number of electrons are less than the number of protons Group 1 metals  ion 1+ Group 2 metals  ion 2+ Group 13 metals  ion 3+

Formation of Sodium Ion Sodium atom Sodium ion Na  – e   Na ( = Ne) 11 p + 11 p + 11 e - 10 e

Formation of Magnesium Ion Magnesium atom Magnesium ion  Mg  – 2e   Mg (=Ne) 12 p + 12 p + 12 e- 10 e

Some Typical Ions with Positive Charges (Cations) Group 1Group 2Group 13 H + Mg 2+ Al 3+ Li + Ca 2+ Na + Sr 2+ K + Ba 2+

Learning Check A. Number of valence electrons in aluminum 1) 1 e - 2) 2 e - 3) 3 e - B. Change in electrons for octet 1) lose 3e - 2) gain 3 e - 3) gain 5 e - C.Ionic charge of aluminum 1) 3- 2) 5- 3) 3 +

Solution A. Number of valence electrons in aluminum 3) 3 e - B. Change in electrons for octet 1) lose 3e - C.Ionic charge of aluminum 3) 3 +

Learning Check Give the ionic charge for each of the following: A. 12 p + and 10 e - 1) 02) 2+3) 2- B. 50p + and 46 e- 1) 2+2) 4+3) 4- C. 15 p + and 18e- 2) 3+ 2) 3-3) 5-

Ions from Nonmetal Ions In ionic compounds, nonmetals in 15, 16, and 17 gain electrons from metals (anions) Nonmetal add electrons to achieve the octet arrangement Nonmetal ionic charge: 3-, 2-, or 1-

Fluoride Ion unpaired electronoctet     1 - : F  + e  : F :     (= Ne) 9 p+ 9 p + 9 e- 10 e ionic charge

Ionic Bond Between atoms of metals and nonmetals (usually) with very different electronegativity Electronegativity difference e.d. > 1.7 Bond formed by transfer of electrons Examples; NaCl, CaCl 2, K 2 O

Ionic Bonds: One Big Greedy Thief Dog!

Ionic bond – electron from Na is transferred to Cl, this causes a charge imbalance in each atom. The Na becomes (Na+) and the Cl becomes (Cl-), charged particles or ions.

What are some characteristics of an ionic bond? 1.Crystalline at room temperatures 2.Have higher melting points and boiling points compared to covalent compounds 3.Conduct electrical current in molten or solution state but not in the solid state 4.Polar bonds

What is a crystalline solid? What does it look like? A crystal or crystalline solid is a solid material whose constituent atoms, molecules, or ions are arranged in an orderly repeating pattern extending in all three spatial dimensions.

Covalent Bond Between nonmetallic elements of similar electronegativity. Formed by sharing electron pairs Examples; O 2, CO 2, C 2 H 6, H 2 O, SiC

What are some characteristics of a covalent bond? 1.Covalent bonds have definite and predicable shapes. 2.Very strong 3.Low melting and boiling points

Covalent Bonds can have multiple bonds, so you should be familiar with the following… Single Covalent Bond- chemical bond resulting from sharing of an electron pair between two atoms. Double Covalent Bond- chemical bond resulting from sharing of two electron pairs between two atoms. Triple Covalent Bond- chemical bond resulting from sharing of three electron pairs between two atoms.

Thought Lab: Ionic or Covalent? With the person sitting next to you, take a look at the following chart and fill in the blanks The compounds used were: Ethanol, Carbon tetrachloride, Glucose, sodium chloride, Water Potassium permanganate

Experimental Results water covalent NaCl ionic Potassium permanganate ionic glucose covalent Carbon tetrachloride covalent ethanol covalent

when electrons are shared equally NONPOLAR COVALENT BONDS H 2 or Cl 2

when electrons are shared but shared unequally POLAR COVALENT BONDS H2OH2O

Polar Covalent Bonds: Unevenly matched, but willing to share.

- water is a polar molecule because oxygen is more electronegative than hydrogen, and therefore electrons are pulled closer to oxygen.

c What is polar covalent? Polar covalent is a description of a bond that has an uneven distribution of charge due to an unequal sharing of bonding electrons.

Electronegativity (EN) a measure of an atoms ability to attract electrons in a chemical bond. a property of an atom involved in a bond

How can we use electronegativity to predict bond type? When two atoms form a bond the difference in electronegativity (ΔEN) can help to determine the bond type. | | |

Examples: HCl = 0.96 Polar Covalent CrO = 1.78 Ionic Br = 0 Covalent

Trigonal Planer Tetrahedral Linear Octahedral Trigonal Bipyramidal Notice all the different types of shapes that the atoms can take on because of their bonding… VSPER

Put the bonding and VSPER shapes together to determine the polarity of a molecule to determine the properties of a substance.