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Energy Most text definitions are along the lines of: Energy is the ability to do work!??????? Energy causes change??? The fact is, no one can simply define what Energy is! Really! Energy is a property or characteristic (or trait or aspect?) of matter that makes things happen, or, in the case of stored or potential energy, has the "potential" to make things happen.
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Basic Chemistry for Rusty Scientists
Matter
• Stuffsolids
liquids
gases
Energy Most text definitions are along the lines of:
Energy is the ability to do work!???????
Energy causes change???
The fact is, no one can simply define what Energy is! Really!
Energy is a property or characteristic (or trait or aspect?) of matter that makes things happen, or, in the case of stored or potential energy, has the "potential" to make things happen.
Atoms
• Atoms : the characteristic particle of an element and the basic building block of all matter.
Molecules• Molecules: the fundamental unit of an
element or compound.
Elements
• Pure substances composed of only one type of particle
• ie atoms.• There are about 90 naturally occurring elements.
• T Lereh Periodic table
Elements
Compounds
• Pure substances composed of 2 or more elements
Some molecules of compounds
Mixtures
• Substances composed of a variety of elements and/or compounds
Two significant mixtures
The Air: – nitrogen – oxygen – carbon dioxide – nitrous oxide – sulphur dioxide– etc, etc
Sea Water:• water• oxygen• carbon dioxide• sodium chloride• magnesium chloride• sodium sulphate • etc, etc
• e
Covalent bonding
Shared outer electrons shared equally
Shared outer electrons shared un equally results in a polar molecule
Ionic bondingSome atoms tend to gain electrons from other atoms gaining a slight –ve charge - negative ions Other atoms tend to lose electrons to other atoms losing a slight –ve charge results in a – positive ions
Water is a polar molecule
Water is a polar molecule Bonds between hydrogen and oxygen within the one molecule are polar
covalent bonds
Bonds between hydrogen of one molecule and oxygen of another molecule due to the difference of electrical charge are called hydrogen bonds.
Because of its polarity and wedge shape water molecules are particularly good at breaking up the ionic bonds of many substances
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