Properties of WaterProperties of Water

Why does ice float?A.Because it evaporates at

100°CB.Because it forms pockets of

empty space when frozenC.Because it is a universal

solventD.Because it melts at 0°C

Why does ice float?A.Because it evaporates at

100°CB.Because it forms pockets of

empty space when frozenC.Because it is a universal

solventD.Because it melts at 0°C

Which best describes the movement of water molecules in a glass of liquid water?A. The molecules all move at the

same speedB. The molecules all move at

different speedsC. The molecules are not movingD. The molecules only move when

you move the glass of water.

Which best describes the movement of water molecules in a glass of liquid water?A. The molecules all move at the

same speedB. The molecules all move at

different speedsC. The molecules are not movingD. The molecules only move when

you move the glass of water.

Think pair shareThink pair share

Do you know what the term polar means? How do you think polar relates to

molecules?

Do you know what the term polar means? How do you think polar relates to

molecules?

What is water? What is water? Think-Pair-Share with your table mates

to answer the questions below

What is the chemical formula for water?

What does the formula tell us about water?

What kind of chemical bond do you think water has?

Think-Pair-Share with your table mates to answer the questions below

What is the chemical formula for water?

What does the formula tell us about water?

What kind of chemical bond do you think water has?

What water is made of… H2O

What water is made of… H2O

Stop at 3 min 50 sec.

Video notesVideo notes

Electrolysis breaks water apart into

2 parts hydrogen and 1 part oxygen

Electrolysis breaks water apart into

2 parts hydrogen and 1 part oxygen

Water’s covalent bondsWater’s covalent bonds Sometimes in covalent bonds there is

an unequal sharing of electrons in a molecule.

When this happens, atoms pull more strongly on the shared electrons than other atoms do.

As a result the electrons move closer

to one atom, causing atoms to have slight electrical charges.

One side of the molecule is slightly negative and the other is slightly positive

Sometimes in covalent bonds there is an unequal sharing of electrons in a molecule.

When this happens, atoms pull more strongly on the shared electrons than other atoms do.

As a result the electrons move closer

to one atom, causing atoms to have slight electrical charges.

One side of the molecule is slightly negative and the other is slightly positive

Polar MoleculesPolar Molecules- Molecules with unequal electron sharing

are called polar molecules

- Polar molecules have a strong attraction to one another because of their slightly charged sides. - (just like opposite ends of a magnet)

- Molecules with unequal electron sharing are called polar molecules

- Polar molecules have a strong attraction to one another because of their slightly charged sides. - (just like opposite ends of a magnet)

Are all covalent bonds polar?

Are all covalent bonds polar?

Not all covalently bonded elements are polar, only the ones with unequal sharing.

A molecule can be nonpolar if… it contains positive and negative charges

that cancel each other out

Not all covalently bonded elements are polar, only the ones with unequal sharing.

A molecule can be nonpolar if… it contains positive and negative charges

that cancel each other out

A polar moleculeA polar moleculeWater is a polar molecule and looks

like this…Water is a polar molecule and looks

like this…

Electrons are pulled more towards the nucleus of the oxygen

Polar molecule videoPolar molecule video

Video notesVideo notes

The attraction atoms have for electrons varies.

Polar molecules have positive and negative poles like a battery or a magnet.

The attraction atoms have for electrons varies.

Polar molecules have positive and negative poles like a battery or a magnet.

Why does it matter that water is polar?

Why does it matter that water is polar?

Water’s charged sides attract other elements and compounds with their charges. For example: a negative ion like chlorine would be

attracted to the positive end of a water molecule (the H or hydrogen side)

Water’s charged sides attract other elements and compounds with their charges. For example: a negative ion like chlorine would be

attracted to the positive end of a water molecule (the H or hydrogen side)

Water the Universal solvent

Water the Universal solvent

The polar charge that develops across the water molecule helps make it an excellent solvent. Solvent- a liquid that allows solids to break

apart to become a well mixed solution.

This is why water is called the Universal Solvent. Water can dissolve more substances than

any other liquid

The polar charge that develops across the water molecule helps make it an excellent solvent. Solvent- a liquid that allows solids to break

apart to become a well mixed solution.

This is why water is called the Universal Solvent. Water can dissolve more substances than

any other liquid

Salt (NaCl) dissolved in water

Salt (NaCl) dissolved in water

Salt contains sodium ions Na+ and chlorine ions Cl-

Sodium is attracted to oxygen end of H2OChlorine is attracted to hydrogen end of H2O

this can also be seen on pg 180 of your textbookCLICK HERE FOR SALT WATER ANIMATION