Properties of DHMO Day 1

On your whiteboard, describe how an atom is different from a Molecule and a Compound.

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Welcome back to atomic theory! Let’s review…

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ANYTHING with more than 1 atom bonded, is a molecule

Notes: What are chemical bonds?

Bonds are forces that hold atoms together in molecules.

Energy is absorbed to break bonds and released when
bonds are made.

Some are stronger than others.

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Notes: VERY BRIEFLY Why Do Atoms Form Bonds?

Answer: Valence Electrons. All atoms want a complete outermost
energy level (2, 8, 16, 32). The further from that they are, the less
stable they are, and the more reactive they get.

Atoms will make different bonds with different atoms to ensure, in any configuration, they can get their outermost energy level filled.

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Notes: VERY BRIEFLY How Do Atoms Form Bonds?

Most bonds are something called a Covalent Bond, where atoms will share the electrons with other atoms to ensure a full electron shell for all atoms in the bond.

This can happen with one pair, 2 pairs, or
even 3 pairs of electrons! The more pairs of electrons in a bond, the stronger the covalent bond gets.

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The Bigger the atom, the Stronger the atom

The Stronger the atom, the more electrons it hogs

The more electrons it hogs, the more negative it is

Notes:VERY BRIEFLY What does a covalent bond look like?

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Notes: What are different kinds of covalent bonds?

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Remember that Covalent Bonds are formed by atoms sharing electrons in a chemical bond to fulfil their energy levels.

This can be done equally or unequally.

In unequal sharing, the bond is called a Polar Covalent Bond (polar means having opposing ends, like a magnet’s poles), and this causes a partial charge.

In equal sharing, the bond is called a Nonpolar Covalent
Bond, and does not cause any charges.

Notes: How do Polar Covalent Bonds Work?

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Different types of atoms exert different forces and levels of attraction on the electrons in their bonds. The strength of attraction an atoms has to its electrons is related to the size of
the atoms, the charge of the nucleus, and the total
number of electrons it has.

In a Polar Covalent Bond, this difference in levels of
attraction affects the product of the chemical reaction,
making one end more positive (the “weaker” atom[s]) and
one end more negative (the “stronger” atom[s]). Think of it
like a tug-of-war that one side is winning.

A great everyday example of this is water. This is also why some substances can dissolve in water and others can’t.

Notes: What are Hydrogen Bonds?

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Hydrogen bonds are weak bonds that occur when oppositely
charged regions of different molecules are attracted to each
other.

These bonds are represented by dotted lines in molecular
diagrams -------------------

How does water orient itself? Opposite charges attract each other.

The partial negative poles of the covalent bonds (O) are attracted to the partial positive poles of the covalent bonds (H)

We can sum this up as Hydrogen Bonds are attraction between different water molecules. This gives water very special properties and behaviors.

Notes: How do Hydrogen Bonds Affect Water?

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Water being polar has an affect on its behavior because the
partial charges at each pole create magnetic fields. Opposites
attract, same sides repel. This forces water into certain arrangements and gives it properties/behaviors we will go over next lesson!

EXIT TICKET:

Explain how Water's structure affect its behavior

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