2-1, Part 6: The Electric World of Atoms and Ions

The Electric World of Atoms

2-1, Part 6 Notes & Practice (CP Chem)

Charges

Protons and electrons are responsible for the overall charge of the atom/ion.

• Nucleus: The nucleus has a positive charge because it contains protons. (Remember, n⁰ don't have a charge!)

• Electron Cloud: The electron cloud has a negative charge because it contains electrons.

Atoms vs. Ions

• Equal: When the number of protons is equal to the number of electrons, the overall charge is 0 (neutral). It is an atom.

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​ATOM: We only use the term “atom” when the number of protons is equal to the number of electrons. If you see the word “atom”, you know that protons and electrons are EQUAL and the charges cancelled out. (Another way to say "cancelled out" is "balance out".)

Protons or electrons?

NOT EQUAL:  It will have a charge and must be referred to as an “ION”. 

• ION:  used to describe an atom that has either more or less electrons (than a neutral atom) and the number of protons and electrons are NOT equal.

Two Types of IONS:  Cations & Anions

CATION: atoms that give away or donate electrons end up with more protons (+)  than electrons (-) .

• This gives them a positive charge.

• Trick: The t in the middle of the word “cation” looks like a plus sign.

ANION:  atoms that gain electrons end up with more electrons (-) than protons (+).

• This gives them a negative charge.

• Trick: The n in the word “aNion” is the first letter of the word negative.

Multiple Choice

Which of the following would be considered an anion?

• 12 p⁺, 10 e^-

• 1 p⁺, 1 e^-

• 15 p⁺, 18 e^-

Multiple Choice

Which of the following would be considered an atom?

• 6 p⁺, 6 e^-

• 1 p⁺, 0 e^-

• 17 p⁺, 18 e^-

Multiple Choice

Which of the following would be considered a cation?

• 13 p⁺, 13 e^-

• 13 p⁺, 10 e^-

• 16 p⁺, 18 e^-

Think about what you know when you see the words ATOM, CATION, and ANION.

After you have filled this chart into your packet on your own, bring it up to me so I can check your understanding.

DETERMINING NET (OVERALL) CHARGE OF AN ION:

If p⁺ = e, then the charge is 0 (neutral).

If p⁺ ≠ e, then ask TWO questions to determine the charge of the ION:

• “What is there more of: p⁺ or e^-?”

  • This tells you which SIGN to write (+ or -).

AND

• “How many more?”

  • This will be the NUMBER that you will write after the sign.

Complete this chart in your packet.

​“What is there more of: p⁺ or e^-?”

• This tells you which SIGN to write (+ or -).

  AND

“How many more?”

• This will be the NUMBER that you will write after the sign

Writing Charges

Charges are written on the top right of the symbol.

• Sign: Ask 'What is there more of: p+ or e-?'

  • Write a + or - sign on the top right of the symbol.

• Number: Ask 'How many more?'

  • Write a number on the right of the + or - sign.

Writing Charges

Practice & check your understanding!

1) Apply what you have learned in this section to complete the chart in your notes.

2) Have me check your work for understanding.

3) Complete the "Take Away Ideas" for this section.