CHAPTER 3.1 Chemistry of Life

Matter – anything that has mass and takes up space. Energy is anything that brings about change. Energy can either hold matter together or take matter apart.

ATOMS  Matter is made of atoms. The atom is made of protons and neutrons (they make up the nucleus, or middle of the atom) and electrons.  Protons are positively charged  Neutrons are neutral (no charge)  Electrons are negatively charged

ELEMENTS  Element – something that is made of only one type of atom. An element cannot be broken down into simpler substances.  The element oxygen, for example, is made only of oxygen atoms.  The periodic table of elements contains all of the elements.

 You are made of elements.  The table tells you how much of each element is in the human body.

COMPOUNDS AND MOLECULES  Compounds are made of 2 or more elements.  For example water is always 2 hydrogen atoms attached to 1 oxygen atom.  Compounds act differently (have different properties) from the elements that make up the compound.  There are 2 types of compounds – ionic and molecular

MOLECULAR COMPOUNDS  The smallest part of a molecular compound is a molecule.  A molecule is a group of atoms held together by sharing electrons.  Example: water –the 2 hydrogens share electrons with oxygen.

IONS  Atoms are usually neutral (no charge), but if they lose or gain electrons they have a charge. Atoms that lose an electron become a positively charged ion. Atoms that gain an electron become a negatively charged ion.

IONIC COMPOUNDS  Ions that are oppositely charged are attracted to each other.  Example: Sodium (Na) ions are positively charged and chlorine (Cl) ions are negatively charged. They will be attracted to one another and form table salt (sodium chloride).  Ions are very important in the human body. They send different messages. You nerves transmit signals through moving sodium and potassium ions.

MIXTURES  Mixture – a combination of substances where the individual parts keep their own characteristics. Like a salad – they are combined but each part stays the same.  One mixture is a solution – salt water is a solution. A solution has 2 or more substances that are mixed evenly.  Suspension are mixtures where the parts can separate easily. Blood is an example.

ORGANIC COMPOUNDS  Organic compounds always contain hydrogen and carbon. They are only found in living things or things that once came from living things.  There are 4 types of organic compounds: carbohydrates, lipids, proteins, and nucleic acids.

CARBOHYDRATES  Supply energy for cell processes  Sugar and starches are carbohydrates

LIPIDS  Do not mix with water  Commonly called fats, oils, or waxes  They store energy and one type of lipid is a phospholipid that is very important part of the cell membrane.

PROTEINS  Made up of amino acids  They are building blocks and make up cell membranes  A special type of protein is an enzyme – they regulate (help make them happen) chemical reactions

NUCLEIC ACIDS  Store important coded information  2 types: DNA and RNA – store genetic information

INORGANIC COMPOUNDS  Made from elements other than carbon.  Important for living things  Examples: water, calcium phosphate, hydrochloric acid, sodium bicarbonate, and salts.

IMPORTANCE OF WATER  Living things are made of more than 50% of water.  All living things chemical reactions happen in water.  Water is good for transport

CHARACTERISTICS OF WATER  Water has a unique property where one end is slightly positive and one is slightly negative. This makes one water molecule stick to another. That gives water surface tension.  It takes a lot of heat to break water molecules apart. This is important because it means that the water helps keep temperature constant.  Ice floats on liquid water. This is because ice has crystals that make it less dense than liquid water. Floating ice provides insulation from very cold temperatures in lakes, streams, and oceans.