a substance made up of one type of atom

A substance formed by the chemical combination of two or more elements in a definite proportion 

4 elements that compose 96% of living matter

carbon, hydrogen, oxygen, and nitrogen

• Center of an atom is called the nucleus
• Protons have positive charge, located in nucleus, have atomic mass units
• Neutrons have no charge, located in nucleus, have atomic mass units
• Electrons have negative charge, located in electron cloud outside of nucleus, have virtually no mass

• Electrons are transfered from one atom to another
• Occurs between a metal and a non-metal

• electrons are shared between atoms
• occurs between two non-metals 

anything that contains carbon

something that does not have the element of carbon

• water expands as it freezes, which means ice is less dense than liquid water, causing it to float to the top of lakes and rivers
• water is a polar because there is an uneven distribution of electrons between the hydrogen and oxygen atoms

• oxygen atom of a water molecule is slightly negative and hydrogen atom is  slightly positive

• water expands as it freezes, which means ice is less dense than liquid water, causing it to float to the top of lakes and rivers
• water is a polar because there is an uneven distribution of electrons between the hydrogen and oxygen atoms

Structure of a water molecule 

• oxygen atom is slightly negative
• hydrogen atom is slightly positive

• Water is extremely cohesive, or attracted to other water molecules, because of its ability to form multiple hydrogen bonds; insects are able to walk on the surface of a pond because of the water molecules being drawn inward
• Water is adhesive, or attracted to molecules of other substances. This is seen between water and glass when their molecules' adhesion causes the water to rise out of a narrow tube against the force of gravity, which is called capillary action

• has 4 valence electrons and each can join with another atom to form a strong covalent bond

• Carbon atoms can bond with other carbon atoms to form chains almost unlimited in length
• These bonds can form single, double, or triple covalent bonds 
• Chains of carbon can close upon themselves to form rings

• Carbohydrates: monosaccharides(simple sugars)
• Lipids: fatty acids and glycerol
• Proteins: amino acids
• Nucleic acids: nucleotides

• Carbohydrates: main source of energy, used by plants for structure (ex. sugar, starches)
• Lipids: store energy, chemical messengers, important parts of membranes (ex. fats, oils, waxes, steroids)
• Proteins: form bones and muscles, regulate cell processes, control rate of reaction, and transport things in and out of cells (ex. meat, dairy, beans, nuts, soy products)
• Nucleic acids: store and transmit hereditary information (ex. DNA, RNA) 

• Fats, oils, waxes, steroids = lipids
• Sugars and starches= carbohydrates
• Meat, nuts, beans, dairy, soy= proteins 
• DNA and RNA= nucleic acids

• 5-carbon sugar
• nitrogenous base
• phosphate group

• Carbohydrates have C, H,O (1:2:1 ratio)
• Lipids have C, H, O but mostly C and H
• Proteins have C, H, O, N, sometimes S
• Nucleic acids have C, H, O, N, P

• Carbohydrates: pasta, bread, etc.
• Lipids: fats, oils, etc,
• Proteins: meat, nuts, dairy, beans, soy, etc.
• Nucleic acids: no food contains them