Chemistry Chapter 7 Study Guide: Ionic Compounds & Bonding

What's the mnemonic for the polyatomic ions we need to know?

Nick (the) camel served clam (in) Phoenix

Nick - nitrogen, camel - carbon, served - sulphur, clam - chlorine, Phoenix - phosphorus

How do you use Nick the Camel?

-Take one of the words (Nick, for ex)

1) First letter + O: NO

2) # of consonants = # of O's: Nick (3) --> NO₃

3) # of vowels = charge: Nick (1) --> NO₃⁻¹ (charge is always negative except ammonium)

-If you want to find the name of it, use the element prefix + "ate" or "ite" --> nitrate or nitrite

Chemical bond

Holds compounds together

Why do atoms bond?

-To become more stable

-To obtain a full outer energy level (8 ve)

Types of bonds

Ionic and covalent

Ionic vs covalent bonds

Ionic: gaining or losing electrons (for metals and nonmetals)

Covalent: sharing electrons (nonmetals)

Cation vs. anion

Cations are positive, anions are negative

Cations are __________ (metals/nonmetals) and anions are (metals/nonmetals)

Cations are metals, anions are nonmetals

Alkali have ____ valence electron(s). Therefore it's easier for them to _________ (gain/lose). New charge is ______, making it a ________ (cation/anion), with a ion symbol of ______.

1 valence electron; easier to lose; new charge is +1; becomes cation, ion symbol is X⁺¹

Alkaline earth metals have ____ valence electron(s). Therefore it's easier for them to _________ (gain/lose). New charge is ______, making it a ________ (cation/anion), with a ion symbol of ______.

2 valence electrons; lose; new charge +2; cation; X⁺²

Transition metals have ____ valence electron(s). Therefore it's easier for them to _________ (gain/lose). New charge is ______, making it a ________ (cation/anion), with a ion symbol of ______.

2 valence electrons; lose; new charge +1 to +7; cation; X⁺¹⁻⁷

The nitrogen group has ____ valence electron(s). Therefore it's easier for them to _________ (gain/lose). New charge is ______, making it a ________ (cation/anion), with a ion symbol of ______.

5; gain; -3; anion; X⁻³

The halogens have ____ valence electron(s). Therefore it's easier for them to _________ (gain/lose). New charge is ______, making it a ________ (cation/anion), with a ion symbol of ______.

7; gain; -1 anion; X⁻¹

Electron configuration for ions

-Regular electron configuration except you gain/lose however many electrons you need to make a stable outer shell (8 ve)

-For example, nitrogen is 1s²2s²2p³ before it bonds. It has 5 ve, so it's easier to gain 3 than to lose 5. Add 3 electrons to the last sublevel part which represents its outer shell - 1s²2s²2p⁶

-This looks like neon's electron configuration but it hasn't become neon, it's only stable like neon (they will always resemble noble gases)

How do you name cations?

Element name + "ion" (lithium ion, potassium ion, etc.)

If it's a transition metal, use the Roman numeral of the charge in parentheses right after the name of the metal

Example: Fe⁺² → iron (II) ion

How do you name anions?

Element name ending in "ide", + "ion" (chloride ion, oxide ion, etc.)

How an ionic bond forms (3 steps)

1) One atom loses electrons (the metal, left side of periodic table)

2) One atom gains electrons (the nonmetal, right side)

3) They are now oppositely charged, attract & bond

Which loses and which gains electrons (metal/nonmetal)?

Metal loses, nonmetal gains

Ionic bond

The electrostatic force that holds oppositely charged particles together in an ionic compound

Properties of ionic compounds

-Form the crystal lattice structure: hard, rigid, brittle

-High melting/boiling points

-Solid state = nonconductor, dissolved in water (aqueous) = good conductor

-Exothermic (releases energy in form of heat when they bond - like when Na and Cl bond, they explode)

Can ionic compounds melt?

No

Which two families do we ignore for ionic compounds?

The carbon family (4 ve) and the noble gases (don't bond, already stable)

These two elements of the carbon family act like transition metals

Tin (Sn) and Lead (Pb)

Formula

The simplest ratio of ions (must be reduced)

Conservation of mass (ions)

Total number of electrons gained by the anion (nonmetal) = the total number of electrons lost by the cation (metal)

Meaning no overall charge, the ionic compound remains neutral

The overall charge of an ionic compound is ______

zero (conservation of mass; same number of electrons from beginning to end)

Monatomic ion vs polyatomic ion

Monatomic: one atom, example: S (sulphide)

Polyatomic: more than one atom (example: SO, sulphate/ite), has a charge. Use Nick the camel to find the individual formula)

-Never change the subscripts within the ion, add parantheses and put the subscript outside, (NO₃)₂ for ex

-Difference: polyatomics always have an O!!

How do you write the formula for an ionic compound?

1) Determine the charges of each ion (using the periodic table, or roman numeral if it is a transition metal)

2) Switch the charges (top of one → bottom of the other)

3) Reduce if necessary

4) Double check (optional) using the dot/ve diagrams, make sure each electron is used

What is the formula for calcium bromide?

CaBr₂

What is the formula for copper (II) phosphide?

Cu₃P₂

What is the formula for magnesium nitrate?

Mg(NO₃)₂

How do you name polyatomic ionic compounds?

Same as binary except use "ate" or "ite". May need to refer to Nick the camel. If it's a transition metal make sure to include the Roman numeral.

Y(NO₂)₃ --> Yttrium (III) Nitrite.

How do you name binary/monatomic ionic compounds?

First element name + second element ending in "ide"

CaF₂ → calcium fluoride

Difference between "-ate" and "-ite"

End the ion with "-ate" if it contains the standard number of oxygen atoms. If it has one less oxygen atom than normal, end with "ite"

Ex: Carbon. Use Nick the Camel to check how many oxygens it needs: since it starts w/ c use "camel". 3 consonants = 3 O's, so it's CO₃. If the formula you are given has CO₃, use carbonate. If it gives you CO₂, use carbonite.

When do you use the suffix "ide"?

Whenever it's monatomic (anions) - NOT for polyatomic ions