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Life is made of matter and matter is anything that occupies space and mass.

MATTER IS COMPOSED OF CHEMICAL ELEMENTS

COMPOUNDS

ELEMENTS

• There are only 25 elements that are essential to life
• Four elements make up 96% of living species; Oxygen, Carbon, Nitrogen, and Hydrogen

TRACE ELEMENTS

• Essential, but only in minute quanties
• Some prevent diseases(iron, flouride)
• Used in food(preserve it, make it look better

ATOM

• Each element is made of one kind of atom
• Smal units of matter that still retains properties of elements
• There are three subtonic particles in an atom

THREE SUBATONIC PARTICLES

• Protons- Positively charged
• Electrons- Negatively charger(Only one involved in chemical activity)
• Neutrons- Electrically neutral

NUCLEUS

• Neutrons and protons pack into an atom's nucleus
• Electroms orbit around it

ELECTRONS

• Occur in energy levels called electron shells
• An atom may have 1-3 electron shells( The number depends on how much chemical properties the atom has)
• Atoms with no outer shell react together: sharing, donating, receiving electrons
• With that process, atoms stick together forming a chemical bond

CHEMICAL BONDS

• The strongest is the covalent bond
• 2 or more atoms held together by a covalent bond make a molecule

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WATER

• Has atoms with different electronegativities
• Electroms spend more time near oxygen forming a polar covalent bond
• Water is a polar molecule

IONIC BOND

• An Ion is a molecule or atom that is electrically charged
• 2 ions that have opposite charges attract together to make a ionic bond
• Salt is a synonym for ionic compound

HYDROGEN BOND

• Weak bonds that are important
• Hydrogen is positively charged
• A positively charged region has a hydrogen atom it is a hydrogen bond

CHEMICAL REACTIONS

• Make or break chemicals bonds
• Do not create or destroy matter, but simply rearrange them

PHOTOSYNTHESIS

COHESION

• The tendency of molecules of the same kind to stick together
• Much stronger for water than other liquids
• Plants depend on it
• Related to surface tension( A measure of how difficult it is to break the surface of a liquid)

HEAT AND TEMPERATURE

• Heat- Energy associated with the movement of atoms and molecules of matter
• Temperature- Measurement of the intensity of heat

EVAPORATE COOLING

WATER IS THE SOLVENT OF LIFE

• Liquid that consists of 2 or more mixtures of substances is a liquid
• Solvent- Dissolving agent
• Solute- Solution that is dissolved
• Aqueous solution - One where water is the solvent. A small percentage of water molecules break into ions

CHEMISTRY OF LIFE

• A compound that releases H+ to a solution is an acid
• H + that is accepted is a base
• A ph scale shows how acidic or basic a solution is