Review of Basic Chemistry Chapter 2

What is Biochemistry? Biochemistry – the study of the chemical substances and vital process occurring in living organisms. Biochemistry allows us to understand how the body works. Ex. Your body breaks down food and makes ATP for energy through chemistry.

Essential Elements Most organisms are made of: 1. Hydrogen (H) 2. Oxygen (O) 3. Nitrogen (N) 4. Carbon (C)

Vocabulary Element - substance composed of one type of atom only. Ex. Na Atom – smallest part of an element that possesses all the properties of the element. Proton – particle in the nucleus with a positive charge of +1. Neutron – a non-charged particle found in the nucleus.

Vocabulary Electron – negatively charged particle -1. Weighs only a fraction of the proton and neutron. Isotope - atoms with the same number of protons and electrons, but different numbers of neutrons.

Organic and Inorganic Chemistry Organic – contains carbon. Exceptions – CO 2 and CO Inorganic – do not contain carbon

Defining Characteristics of Matter Matter is anything that occupies space, has mass and possesses the property of inertia. Inertia – a body remains in the same state of motion until an outside force acts upon it.

Forms of Matter Solid, liquid, gas The form of a substance is determined by the potential energy of the molecules. The more energy, the quicker the molecules move. There is more energy in a liquid than in a solid.

Electrons Electrons are found outside of the nucleus in orbitals. Chemical reactions involve sharing or exchanging electrons. Valence Electrons – electrons found in the outermost energy level

Carbon The first orbital can hold 2 electrons. The next can hold up to 8. Because carbon’s atomic number is 6, it has 6 protons and 6 electrons.

Stability Elements are stable when the outer electron level is full or has 8 electrons.

Energy When bonds form, energy is stored in that bond. When bonds break, energy is released. 2 hydrogen atoms bonded together need 104 kcal/mole to break.

Covalent Bonds ElementNumber of Covalent Bonds Hydrogen1 Oxygen2 Nitrogen3 Carbon4 Sulfur2

Molecules and Compounds Molecule – two or more atoms of the same type chemically combined. Ex. O 2 Compound – two or more different atoms chemically combined. Ex. HCl

Covalent and Ionic Covalent bonds – share electrons. Ex. O 2 Ionic bonds – formed by transferring electrons. Ex. NaCl (sodium chloride)

Electronegativity Oxygen has a stronger pull on electrons because it is more electronegative. Oxygen has an electronegativity of 3.5. Hydrogen’s affinity is only 2.1

Salt Salt is sodium chloride or NaCl. Sodium chloride is formed when sodium donates an electron to chlorine. This is an ionic bond.

Importance of Water Covalent bonds hold a water molecule together through 2 pairs of shared electrons. Bohr model of water

Importance of Water “Polar” means that the electrons are not evenly shared between the atoms. Oxygen is partially negative because it has a greater pull on the electrons than hydrogen. Oxygen is slightly negative, hydrogen is slightly positive.

Importance of Water Since the oxygen atoms are slightly negative and the hydrogen atoms are slightly positive, there is an electrostatic attraction between the positive and negative ends of two molecules. This results in a hydrogen bond holding two water molecules together.

Importance of Water Water has the ability to dissolve other molecules due to the fact that water is a polar molecule. It surrounds negative atoms with the positive hydrogen ends and positive atoms with the oxygen ends. This is why it is called the universal solvent.

Importance of Water Properties of water: 1. Ice floats (water expands as it freezes) 2. High heat of vaporization (a lot of energy to go from liquid to gas) 3. High specific heat (a lot of energy is required to raise the temp.) 4. Universal solvent 5. Hydrophobic effect (water pushes non-polar molecules together) Water will not interact with non-polar molecules

Acids and Bases Acid – molecules that split apart in water and release hydrogen ions (H+) Base – molecules that split apart in water and release hydroxide ions (OH-)

Acids and Bases Buffer – substance that helps keep body solutions at the proper pH level releasing H+ or OH-. Bicarbonate and Carbonic acid are the most common buffers in the human body. Buffers maintain homeostasis.