Thursday's class 2-3

• ​Ionic compound ​

• Covalent compounds

• Molecular geometry

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• Atomic structure

  • Protons, electrons, neutrons, energy levels​

• ​Periodic table

  • Isotopes, atomic mass, atomic number, electronegativity , empirical vs molecular formula

• Molecular geometry ​

• Ionic compounds

  • Writing chemical formulas and characteristics

• Covalent compounds

  • Polarity and characteristics ​

​Topics

• ​Transferring of electrons

• Formation of salts

• No actually 'bonds'. Held together by opposite charges

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Transferring of electrons from one element to another resulting in oppositely charged ions.

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Ionic Bonding

​Recap video (optional)

• Electrons transfer from a metal to a nonmetal

• Electron transfer results in one negatively charged ion ​(anion) and one positively charged ion (cation)

​Characteristics

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​Lewis dot periodic table shows this

​Ionic bonds - Writing chemical formulas

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For Ionic bonding​

1. Cation first (+ ion)

2. Anion second (- ion)

3. Subscripts representing ratio between cation and anion

4. Check that charges balance out - Do not include charges in equation.

​Ionic bonds - Writing chemical formulas

​Replace with sub-header

For Ionic bonding​

1. Cation first (+ ion)

2. Anion second (- ion)

3. Subscripts representing ratio between cation and anion

4. Check that charges balance out

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Rules

1. Cation first (+)

2. Anion second (-)

3. Use chemical symbols ​

4. No charges included

5. Subscripts used to express ratio between cation and anion​ in the empirical (simpilest) formula.

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Writing chemical formulas

Chemistry

​Have Periodic table and electronegativity chart out

​Covalent bonding

Key concepts:

• Nonmetal with a nonmetal

• Electrons are being shared

• Polar or nonpolar based on electronegativity of elements bonded

• All elements still want to fill outer shells (octet rule!) ​

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• Electronegativity is the key

• more specifically, the DIFFERENCE in electronegativity....

• ​Electronegativity is the strength that an atom can pull electrons.

• DEN Range is the difference in electronegativity values between atoms

• Determines the type of bond

• Covalent bonds have similar electronegativities

• Ionic bonds have different electronegativities

Electrons are shared

• Nonmetal + Nonmetal

• Make COVALENT bonds

• Share electrons

• Low electronegativity difference

• Have Lower melting and boiling points

• Tend to be flammable

• When dissolved in water they do not conduct electricity

• Soft or brittle solid

• Can also form crystals

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• A polar molecule is sharing electrons unequally (two different poles, one positive and the other negative)

• A nonpolar is sharing electrons equally (tug of war with two trucks pulling with the exact same force)

• Polar bonds have a difference in electronegativity that is equal to 0.4 or greater

• Nonpolar bonds have a difference in EN of 0.4 or less

• Molecular Polarity is different from the polarity of the bonds

• When a molecule is symmetrical it is nonpolar

• A nonsymmetrical molecule is polar

​Quiz tomorrow

​Before quiz tomorrow

We will go over the basics of molecular geometry. ​

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