Charge of Elements

What's the Charge? (anion and cation)

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Quick Review

• Last class we said ions are any atom that has charge

• The only way to have a charge is to again or lose VALENCE electrons.

• If an atom GAINS electrons they are called anions and have a negative charge

• If an atom LOSES electrons they are called cations and have a positive charge.

Multiple Choice

Which best describes this image?

• anion

• cation

• atom

Multiple Choice

Which best describes this image?

• has 8 valence electrons

• has 2 valence electrons

• has 10 valence electrons

Multiple Choice

Which best describes this image?

• lost 1 electron

• gained 1 electron

• lost 1 proton

• gained 1 proton

Open Ended

What questions do you have?

Octet Rule

• Atoms are most stable with a full valence shell

• Think: Atoms "want" 8 valence electrons.

• Will give away or steal electrons to achieve stability (to get 8 electrons)

Multiple Choice

How many valence electrons does sodium have?

• 1

• 2

• 3

• 4

Multiple Choice

Is sodium stable?

• yes, because it is neutral

• no, because it has not achieved the octet rule

Multiple Choice

What should sodium do to achieve the octet rule?

• lose 1 valence electron

• gain 1 valence electron

• gain 7 valence electrons

• lose all of its electrons

Open Ended

What question do you have?

Multiple Choice

How many valence electrons does sulfur have?

• 4

• 5

• 6

• 7

Multiple Choice

Is sulfur stable?

• yes, because it is neutral

• no, because it has not achieved the octet rule

Multiple Choice

What should sulfur do to achieve stability?

• lose 6 electrons

• gain 6 electrons

• lose 2 electrons

• gain 2 electrons

Multiple Choice

Which was an example of a cation?

• Sodium

• Sulfur

Open Ended

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Rules for Predicting charges of metals

• Metals will lose all their valence electrons...

• Have 1 valence electron? Lose it! Become a +1 cation

• Have 2 valence electrons? Lose them both! Become a +2 cation

• Have 3 valence electrons? Give them all away! Become a +3 cation.

Multiple Choice

What charge will a calcium ion have?

• +1

• -1

• +2

• -2

Multiple Choice

What charge will an aluminum ion have?

• +3

• +2

• +1

• -2

Multiple Choice

What charge will a potassium ion have?

• +3

• +2

• +1

• -2

Open Ended

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Rules for predicting charges of nonmetals

• Nonmetals will steal enough electrons to have a total of 8 valence electrons.

• Have 5 valence electrons? Go steal 3! Become a -3 anion

• Have 6 valence electrons? Go steal those last 2 your need! Become a -2 anion

• Have 7 valence electrons? So close, go steal 1 more! Become a -1 anion

Multiple Choice

What charge will Chlorine form?

• -3

• -2

• -1

• -7

Multiple Choice

What charge will nitrogen form?

• -3

• -2

• -1

• -7

Multiple Choice

What charge will oxygen form?

• -3

• -2

• -1

• -7

Open Ended

What question do you have?