Unit 6 Covalent Review

Unit 6 Covalent Review

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Bonding!

• Chemical attachment of two or more atoms

• Why? to complete the octet of each element for stability

• Ionic: transfer of electrons between metal and non metal

• Covalent: sharing of electrons between nonmetals

Multiple Choice

Which of these is true?

• Ionic bonds share electrons between metal and nonmetal

• Covalent bonds transfer electrons between metal and nonmetal

• Ionic bonds transfer electrons between two nonmetals

• Covalent bonds share electrons between two nonmetals

How does electronegativity contribute to bonding?

• Nonpolar Covalent: A very small difference (or no difference) in EN (0-0.4) C-H, S-H, same elements. EQUAL SHARING of electrons

• Polar Covalent: Some difference in EN (0.5-1.7) Ex: N-H, C-O, different non-metals UNEQUAL SHARING of electrons

• Ionic: Large difference in EN (greater than 1.7), Metals and nonmetals. TRANSFER of electrons

Multiple Choice

Which of these are correctly paired? (red shows numerical EN difference)

• Na-Cl = covalent bond (greater than 1.7)

• H-H = polar covalent bond (0)

• C-O = polar covalent bond (1.0)

• H-Br = nonpolar covalent bond (0.7)

LAB PROPERTIES

• Nonpolar Covalent: Not soluble in water and not conductive in water; very low melting point

• Polar Covalent: SOLUBLE in water but not conductive in solution; medium melting point

• Ionic: Soluble in water and conductive in solution; high melting point

Multiple Choice

A white solid in the lab is soluble in water but is not conductive in solution. It is most likely:

• Ionic

• Polar Covalent

• Non-polar covalent

Multiple Covalent Bonding

• A single bond C-C involves the sharing of 1 pair (2 total electrons)

• A double bond C=C involves the sharing of 2 pairs (4 total electrons)

• A triple bond C=C involves the sharing of 3 pairs (6 total electrons)

Lewis Dots

• Find the "A" group on the PTable

• That is the number of dots (space out in a square shape)

• Metals lose electrons --> NM

• NM share electrons with a line

Multiple Choice

Which of these is correct for sulfur? (group 6A, atomic # 16)

Multiple Choice

If sulfur bonds with hydrogen (group 1A H∘ ), what is the likely formula?

• HS

• H₂S

• H₃S

• H₄S

Naming Compounds

• Covalent compounds require prefixes to show how many of each element (subscript_number)

• Ionic compounds DO NOT require prefixes (use the charges / oxidation state to determine)

• Transition elements require Roman Numeral to determine charge because they different oxidation states / charges

Multiple Choice

What is the "chemistry" name for water, H₂O

• dihydrogen oxide

• dihydrogen monoxide

• hydrogen oxigide

Multiple Choice

What is the formula for dinitrogen pentasulfide

• N₂S₅

• N₂S₆

• NS

• N₅S₂

Multiple Choice

What is the prefix for 4

• quad

• cuatro

• four

• tetra