The Nature of Matter Mr. Zito The Chemistry of Life The Nature of Matter Mr. Zito

A. All matter is made up of atoms. 1. Atom: the smallest unit of matter that can not be broken down by chemical means. It has all of the chemical and physical properties of the element it makes up.

C. Elements (Periodic Table- agenda) 1. Elements: a pure substance made up of only one kind of atom

B. Structure of an Atom 1. Dense Nucleus- made up of protons (+) and neutrons (0) 2. Outer Cloud- made up of electrons (-) 3. Number of Protons (+) = Number of Electrons (-) There is no net charge.

Elements are distinguished by the number of protons in their nucleus. Atomic number- # of protons Atomic Symbol Atomic Mass= # protons + # neutrons Atomic Number Atomic Symbol Atomic Mass

Atomic Number= Number of PROTONS ______________ Atomic Mass= 14.O1 How many NEUTRONS are in the nucleus? ______________ Atomic Symbol ______________

***Isotopes- contain a different number of neutrons in the nucleus. Changes the Atomic Mass unstable- radioactive Atomic Mass Atomic Number Three isotopes of Lithium: the stable Lithium-6, Lithium-7 and the unstable Lithium-8, which decays via -decay. Each of these isotopes has the same atomic number (Z=3), but a different mass number depending on the number of neutrons (3, 4 or 5

2. There are a small number (25) of elements that are vital to life. A. MVP’s: Carbon, Hydrogen, Oxygen, and Nitrogen make up 98% of biologic matter.

II. Bonding of Atoms NaCl A. Compounds: substances that are formed from the joining of two or more different elements in a definite proportion. NaCl Chemical Formula: represents the elements in the compound and their proportion Ex) Salt, glucose, water

B. Molecule: Smallest particle of a substance which has all of its properties.

It determines the bonding properties Valance numbers are the number of electrons in the last shell or energy level. What is the significance of the valance number? It determines the bonding properties of the atom.

1. Covalent Bonds- “share in pairs” C. Types of Bonds 1. Covalent Bonds- “share in pairs” a. - two or more atoms share electrons to form a molecule. b. - electrons must fill energy levels to make them stable.

c. Nonpolar covalent bond- equal sharing of electrons d. Polar covalent bonds- unequal sharing of electrons

Polar Covalent Bonds occur when the one atom has a greater attraction so the electrons are unequally shared.

Nonpolar are shared equally

2. Hydrogen Bond- weak chemical attractions between polar molecules. a. The positive pole of a molecule is attracted to the negative pole of another molecule. b. type of attraction that allows for the properties of water

3. Ionic Bonds- a.-transfer of electrons which allow oppositely charged particles bond. b. ION- a charged particle that has gained (-) or lost (+)an electron

III. Properties of Water A. Attraction of Water- Hydrogen Bonding 1.Cohesion- attraction of water molecules to other water molecules. a. Makes water “sticky” b. Creates surface tension.

Surface Tension

2. Adhesion- the attraction of water to other surfaces. a. Allows for transport in plants. b. Capillary Action- upward movement of water against gravity.

B. Water has a high Specific Heat 1. Heats up slowly and holds its heat. 2. Allows organisms to regulate and maintain a constant internal temperature.

C. Universal Solvent (does the dissolving) 1. Water is able to easily dissolve polar molecules and charged ions. (solutes- what is being dissolved) 2. The +/- ends or POLARITY of water easily attract the opposite charges. 3. Solutions form from the even distribution of the solute in the solvent. 4. Non- polar molecules have a harder time dissolving ex) Fats

D. Density 1. Hydrogen bonding causes ice to be less dense than water causing it to float. 2. Allows for the insulation of marine animals.

IV. Acid and Bases A. Acid- compound that forms hydrogen ions (H+) when dissolved in water. B. Base- Compounds that reduce the number of hydrogen ions in water by forming OH- or hydroxide ions (Alkaline)

C. pH Scale- tells us how acidic or basic a substance is.

D. Neutralization Acid + Base --------------- Salt + Water E. Buffers- substances that resist changes in pH. - bond to excess H+ or gives off OH-.