By Savannah Fenimore, Will Fyfe and Max Leal

What is Matter and Mass? Matter is what makes up everything in the universe. Matter defined is anything that occupies space and has mass. But what is mass? Mass is the quantity of matter an objet has. Keep in mind mass and matter are two different things and are not interchangeable.

Elements Elements are pure substances that cannot be broken down into any simpler form of matter. There are over 100 discovered elements but less than 30 are important to living things. In fact almost all the mass that makes up living things is made of oxygen, carbon, nitrogen, and hydrogen. The Elements are arranged in a table called the periodic table of the elements. Each element is given a chemical symbol, atomic number, and the atomic mass is shown.

Atoms The simplest particle of an element that retains all the properties of that element is an atom. The different properties of an atom determines the different properties of an element. Atoms are made up of a single nucleus and one or more energy levels. An atom’s nucleus contains protons and neutrons. Most of an atom’s weight is in the nucleus. An atom’s energy level(s) contains electrons.

Atoms cont. Protons contained in the nucleus are positively charged. The number of protons in an atom is called the atomic number of the element. Neutrons in the nucleus have no electrical charge. Electrons in the energy levels are negatively charged. Electrons are small very high-energy particles and move at high speeds. The inner energy level of an atom can only hold 2 electrons. While the outer energy level can hold up to 8. In an element protons are balanced by electrons. So that the overall electrical charge of an atom is zero.

Compounds A pure substance that is made up of atoms of two or more elements is called a compound. In a compound, the proportions of each kind of atom are fixed. The tendency of elements to combine and form compounds depends on the number and arrangement of electrons in their atoms. Generally atoms are unstable in their natural state thus they tend to combine with other atoms. Atoms are most stable when their outer most energy level contains 8 electrons.

Compounds cont. Most atoms in elements do not have 8 electrons in their outer most energy level. So they tend to undergo chemical reactions. Combining in ways that allow them to become stable. During chemical reactions chemical bonds are broken, atoms are rearranged, and new chemical bonds, or attachments are formed.

Covalent Bonds Covalent bonds occur when two atoms share a pair of electrons. For example when an oxygen atom that has 6 electrons in is outer most energy level comes in contact with 2 hydrogen atoms that each have one electron in their energy levels, they can share a pair of electrons and achieve complete stable. A molecule is the simplest part of a substance that retains all the properties of the substance and that can exist in a free state.

Ionic Bonds Ions are atoms with either a positive or a negative charge. Ions occur when an electron from one atom’s outer most energy level is transferred to another atom. Because of this one atom will be positively charged while the other becomes negatively charged. When in the presence of one another they attract and bond together. This is called an ionic bond.

Energy Energy is the ability to do work or cause change. There are various forms of energy and various forms can be converted to other forms. For example electrical energy can be converted into radiant energy(light) and thermal energy(heat). Free energy is related to living systems. Free energy is the energy in a system that is available for work. For example, in a cell, it is the energy available to fuel cell processes.

States of Matter Though it may not appear so, all the atoms and molecules in any substance are in constant motion. The rate at which they move determines what state that substance is in. Solid, Liquid, or Gas. Particles of a solid are linked tightly where they vibrate in place. Particles of a liquid are not tightly linked and move around freely. Particles of a gas are spread far apart and move very rapidly. To cause substances to change states thermal energy must be applied.

Living Things and Chemical Reactions Chemical reactions are essential to all living things. Many are highly complex and are interrelated. When a chemical reaction takes place in living things bonds are broken in compounds and elements are rearranged. After this process new compounds are formed.

Energy Transfer Most of the energy used by our bodies comes from food. Because of this constant chemical reactions take place to break down food compounds into energy. Chemical reactions that involve a net release of free energy are called exergonic reactions. Reactions that involve a net absorption of free energy are called endergonic reactions.

Activation Energy For chemical reactions to take place some energy must be applied to the reactants. The amount of energy needed to start the reaction is called activation energy. A chemical substance known as catalysts can reduce the amount of activation energy needed. Enzymes are an important class of catalysts to living things. One organism may have thousands of enzymes. Each tailor- made for a different chemical reaction.

Reduction-Oxidation Reactions Energy is constantly flowing through living things. The constant flow and transfer of energy means that electrons are constantly transferring between different atoms. The reactions in which electrons are transferred between atoms is called reduction-oxidation reactions or redox reactions. In a redox reaction a reactant loses one or more electrons. Becoming positively charged.

Reduction-Oxidation Reactions cont. Redox reactions have an opposite reaction that follows. In reduction reactions a reactant will gain one or more electrons therefore becoming negatively charged. Redox and reduction reactions always occur together. When a reduction-oxidation reaction occurs, and the electron(s) given up by one substance is then accepted by another substance in a reduction reaction.