Chemistry of Life: Nature of Matter and Water Honors Biology

The Nature of Matter positive 1 nucleus no charge 1 nucleus electrons I. Atom: smallest unit of matter A. Subatomic Particles Particle Charge Relative Mass Location in Atom proton neutron negative positive 1 nucleus no charge 1 nucleus electrons ~0 Outside nucleus Most atoms are neutral because they have equal numbers of protons and electrons. Atoms that lose electrons have a positive charge. Atoms that gain electrons have a negative charge.

Draw the following picture of a Carbon atom: Neutral Atom of Carbon: Protons(+) Neutrons Electrons(-)

Draw the following picture of a Carbon atom: Positive Atom of Carbon: Negative Atom of Carbon: Neutrons Electrons(-) Protons(+)

II. Element: substance made of one type of atom The Nature of Matter II. Element: substance made of one type of atom A. atomic number: #protons: defines an element (also # of electrons in a neutral atom) B. mass number: sum of protons + neutrons in an atom How many neutrons in a Sodium atom? 12

Isotopes: C. isotope: atoms of the same element with different numbers of neutrons D. radioactive isotope: isotope with an unstable nucleus that breaks down over time (emits radiation) uses: dating fossils, diagnosing and treating diseases, killing bacteria in food/ on surgical equipment Nonradioactive carbon-12 Nonradioactive carbon-13 Radioactive carbon-14 6 electrons 6 protons 6 neutrons 8 neutrons 7 neutrons

How to read the periodic table

The Nature of Matter III. Compound: substance formed by the chemical combo of ≥ 2 elements in definite proportions (ex. NH3, NaCl) IV. Chemical Bonds ion: atom that’s gained or lost electrons 1. ionic bond: bond formed by transfer of electrons from one atom to another

The Nature of Matter Sodium atom (Na) Chlorine atom (Cl) Transfer of electron Protons +11 Electrons -11 Charge 0 Protons +17 Electrons -17

The Nature of Matter Transfer of electron Sodium atom (Na) Chlorine atom (Cl) Sodium ion (Na+) Chloride ion (Cl-) Transfer of electron Protons +11 Electrons -11 Charge 0 Protons +17 Electrons -17 Electrons -10 Charge +1 Electrons -18 Charge -1

Nature of Matter 2. covalent bond: bond formed when atoms share electrons molecule: group of atoms covalently bonded together

Van der Waals Forces A slight attraction that develops between the oppositely charged regions of nearby molecules. Example: Newt walking up glass window

Properties of Water 10 10 Oyxgen Atomic # : 8 Hydrogen Atomic #: 1 # of Protons: # of electrons: Overall charge: 10 10

Water: Needed for Life Water has several properties that make it necessary for life. It is POLAR - has area with a slight + charge, and an area with a slight - charge.

Why is water polar?:

Water: Needed for Life Hydrogen Bonding: attractive force between hydrogen and another electronegative atom in a different molecule

Water: Needed for Life Hydrogen Bonding allows one H2O molecule to “stick” to another H2O molecule.

Cohesion ability for water molecules to stick to themselves Water: Cohesion Cohesion ability for water molecules to stick to themselves Surface Tension Beads of Water

Water: Adhesion Adhesion ability for H2O molecules to stick to other materials Meniscus in a graduated cylinder

Water: Adhesion and cohesion allows capillary action

A solvent has the ability to dissolve other materials Water: A Great Solvent Remember… A solvent has the ability to dissolve other materials Water is a solvent for many things For example: The liquid part of your blood (the plasma) is 90% water Some items, such as fats and oils DO NOT dissolve in water.

Mixture: Combo of 2 or more substances that are physically mixed but not chemically combined!! Examples: soil, salsa, trail mix, jello, sugar water.

Types of Mixtures: A. Solution: one substance dissolves in another Won’t separate over time Can’t be filtered Light passes through cleanly Homogenous: uniform, evenly distributed

Parts of a Solution : a. Solute:substance that is dissolved b. Solvent:substance that does the dissolving.

Kool-Aid Solution Solute: Kool-Aid powder Solvent: Water

B. Suspension: mixture of liquid and non-dissolved materials Particles are bigger, visible with naked eye “murky” or “opaque” Particles will settle out Can be separated by filtration

Suspension Heterogenous: not evenly distributed Examples: sand in water, Italian Salad dressing, paint, liquid medicines that requires shaking before being taken

C. Colloid Homogeneous Smaller particles than suspension but bigger than molecules in solution won’t settle out, can’t be separated by filtration scatters light Can’t see materials with naked eye mayonnaise, milk, blood, aerosols, smog, Shampoo, gels

Now test what you learned: Indicate whether each mixture each is a solution, suspension or colloid

The pH scale is used to measure the strength of acids and bases pH: What is it? The pH scale is used to measure the strength of acids and bases

Some properties of acids and bases pH: What is it? Some properties of acids and bases pH Example Characteristics Acids Neutral Bases Lemon vinegar soda, aspirin Sour, burns, dissolves things < 7 Pure Water ------ = 7 Soap, baking soda, ammonia > 7 Bitter, Slippery

H2O H+ + OH-   pH: What is it? Some compounds break up into ions when they dissolve in water. Solutions with more H+ ions are more ACIDIC They have a LOW pH (<7) Solutions with less H+ ions are more BASIC They have a HIGH pH (>7)  H2O H+ + OH- 

pH: Looking at common items Battery Acid pH = 0 Orange Juice pH = 3 Ocean Water pH = 8 Oven Cleaner pH = 13

pH: Importance to Humans Blood has a pH of 7.4 (about neutral) If pH goes below 6.8 or above 7.8 it is deadly! To keep blood at the proper pH - our body uses buffers

pH: Buffers Buffers are weak acids and bases that neutralize, or weaken, strong acids or bases. In blood, buffers prevent pH change. Sodium bicarbonate, or baking soda, is a buffer