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2.2 Properties of Water. Review. An atom is the basic unit of matter Electrons are negatively charged and move around the nucleus Protons are positively charges Neutrons are neutral Protons and neutrons are located in the nucleus The molecule is the smallest unit of a compound.
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Review • An atom is the basic unit of matter • Electrons are negatively charged and move around the nucleus • Protons are positively charges • Neutrons are neutral • Protons and neutrons are located in the nucleus • The molecule is the smallest unit of a compound. • The # protons = the # neutrons
*NEW* There are two types of bonds • Ionic Bond: Occurs between a metal and a nonmetal (+ and -) • There is a transfer of electrons • Covalent: Occurs between two non-metals • Electrons are shared
Types of bonds • Sodium is a metal; when bonded with chlorine, it forms a __________________ bond • Hydrogen acts as a non metal when bonding with oxygen, another non metal. This type of bond is called a _______________ bond • Potassium will form a __________ bond with chlorine • When oxygen bonds with itself, it forms a _________ bond
The Water Molecule • Water is a compound found over most of earth’s surface • Finding liquid water on a planet tells scientists that there could be life on that planet • What properties make water so important?
Water is a polar molecule • Water (H2O)is neutral, meaning there are 10 protons and 10 electrons • The oxygen atom has 8 protons; a hydrogen atom only has 1. • The electrons are pulled more towards the oxygen
Water is Polar • Because water is polar, molecules are attracted to each other • This is due to hydrogen bonds • So what does this mean?
Let‘s find out… • http://www.youtube.com/watch?v=9eaJ8u99A3c • http://www.youtube.com/watch?v=45yabrnryXk • http://www.youtube.com/watch?v=V-cXzZt2iVk
So what does this really look like? • http://www.youtube.com/watch?v=sBZfPmIcS-E
Other “neat” things about water • Cohesion- Because water can have as many as 4 hydrogen bonds, it is very cohesive. Cohesion pulls water molecules together • This is how lizards and water striders can walk on water • Adhesion- this causes water to pull up the sides of glasses and lab equipment. Remember the meniscus song? • Heat capacity- amount of heat energy required to increase a substance’s temperature. • Hydrogen bonds make it hard for water molecules to move faster