Chapter 2 Chemistry
I. Atomic Structure of Matter
- Matter- anything that has mass (weight) and takes up space (volume).
- Element- all matter is made up of elements- a substance that cannot be broken down into smaller substances by chemicals. For example: gold and oxygen. The six most common elements in living organisms are: Oxygen (O), Carbon (C), Hydrogen (H), Nitrogen (N), Phosphorus (P), and Sulfur (S).
- Each element is made up of smaller particles that we call atoms (smallest part of an element that has the same properties as that element).
- Parts of an atom:
- Nucleus- Protons which have a (+) charge and mass, Neutron which has no charge (neutral) and a mass.
- Electrons- form a cloud of electricity around the nucleus. They have a (-) charge and no mass.
- If there is the same number of protons as electrons, we say the atom is neutral. If there are more protons, the atom will have a net (+) charge. If there are more electrons, the atom will have a net (-) charge. We will assume all atoms are neutral (same # of protons as electrons) unless told otherwise.
- Atomic Number and Mass
- Periodic Table of Elements- listing of all the natural as well as man-made elements. When looking at the periodic table, an element will be listed by their symbol and in order based on their atomic number.
- Atomic Number-number of protons in an atom. Ex. O has 8 protons, its atomic number is 8. Note. In a neutral atom #electrons=#protons. All atoms will be neutral unless otherwise stated.
- Atomic Mass- number of protons + the number of neutrons. K atomic number 19, its atomic mass is 39. How many neutrons, electrons and protons does K have?
- Atomic Structure (drawing of an atom): brief review of electron levels (2 first level, 8 second)
Charge/ Mass /
Protons/ Positive (+) / Yes / ------
Neutrons/ None / Yes / ------
Electrons/ Negative(-) / No / ------
#Atomic/ ------ / ------ / # of Protons
Atomic Mass / ------ / ------ / #P + #N
d. Isotopes: An element with the same number of protons but a different
atomic weight. Remember, the number of protons in an element, or its
atomic number can never change, but the number of neutrons can change,
thus altering its weight. For example: there are 2 isotopes for hydrogen.
Normal H has an Atomic Number of 1
Atomic Mass of 1 (0 Neutrons)
Deuterium has an atomic number of 1
Atomic mass of 2 (1 Neutron)
Tritium has an Atomic Number of 1
Atomic Mass of 3 (2 Neutrons)
- Isotopes are used often in science and medicine (radioisotopes-give off radiation) (for example C-14 dating). C-14 is an isotope of Carbon 12.
C. Compound: substance that contains two or more elements chemically combined.
can only be separated by chemical means. Ex: H2O, NaCl
1. Molecule: Smallest part of a compound that still displays all the properties of
that compound. Ex: Water is made up of 2H and 1O. There are millions of
water molecules found in one glass of water.
2. Mixture: individual elements or compounds keep their own properties and can
be separated easily. Ex: Salt Water. Mixture of NaCl and H20.
- Chemical Bonding- how 2 or more atoms join or are held together to form a compound. THINK ELECTRONS
- Ionic Bonds- the transfer of electrons from one atom to another. The result will leave one atom electrically negative and one electrically positive (see overhead).
- Covalent Bonds- the sharing of electrons between 2 atoms.
II. Solutions- mixture in which one or more substances are uniformly distributed in
another substance. Can be solids, liquids, or gases. Ex. Salt & Water
- Solute- substance being dissolved in the solution. (Salt).
- Solvent- substance in which the solute is being dissolved (water). After the salt and water are mixed, do the salt and the water still retain their properties? Can they be separated?
- Concentration- measurement of the amount of solute dissolved in a fixed amount of solution. If you continue to add salt to water, eventually, the salt will no longer be dissolved (more solute then solvent)-we say the solution is now saturated.
- Suspension- a solution in which the solute and solvent mix for a period of time and then separate. Oil & water.
- Acids & Bases
- Acid- is a substance when placed in water that gives off H+ (Hydrogen) ions. These H+ will then recombine with the water to form hydronium ions or H3O+. The more H+ ions released the more hydronium ions dissociated, the more acidic the solution. HCL H+ + Cl-.
- Properties- sour taste, tingling or burning sensation when touched and when concentrated can be very corrosive. Ex. Stomach acid, vinegar, lemon juice, urine
- Base- is a substance when placed in water that gives of OH- (hydroxide) ions. The more OH- ions dissociated, the more alkaline or basic the solution. NaOH Na+ + OH-.
- Properties- bitter taste, slippery to the touch, dissolving agent. Ex. Ammonia, Milk of Magnesia, milk, semen, blood (slightly).
- pH- scale used to measure levels of hydronium and Hydroxide ions. Ranges from 0-14. Where 0-6 is acidic and 8-14 is alkaline. 7 is neutral (water-equal concentrations of hydronium and hydroxide ions).
- Buffer- chemical substance that neutralizes either an acid or a base. Very important in human systems.
- Energy- the ability to do work. It can neither be created nor destroyed. Just transferred from one type of energy to another. Ex. Plants take the suns light energy and transform it into chemical energy (sugar- its food).
- Different forms of energy- light energy, heat energy, electrical energy, chemical energy, and mechanical energy.
- All energy can be classified into either potential or kinetic energy: Potential- stored energy (water at the top of a waterfall). Kinetic- energy of motion (when the stored energy of the water goes over the edge of the waterfall, its energy changes to kinetic energy and the water is filled with moving energy and is very powerful).
- All atoms are in constant motion (kinetic energy). The rate at which they move determines their state: Solid- atoms are bound tightly together and they vibrate in place (6 students close together jumping up and down). Liquid- greater kinetic energy- the atoms are not bound as tightly allowing liquids to form to any shape (have 6 students move together as a group). Gas- great kinetic energy- the atoms have little attraction to one another. How does one change state from a solid to a liquid or a liquid to a gas? Thermal energy.
- Chemical reactions: process of breaking chemical bonds (catabolism) or forming new bonds (anabolism). Ex: Na + CL NaCl
NaCl Na + Cl. In these processes, energy is either released
(exergonic) (exercise energy is released (heat) or absorbed (endergonic)
eat the energy is absorbed or stored in the form of chemical energy.
- Energy of Activation (very important in bio)- amount of energy needed start a reaction (heating water on a flame to boil). In the human body we need to reduce the energy of activation (hurry the process up). We don’t want to wait for the water to go from 40oC to 100oC in 10 minutes we want it to boil faster, so we add what is called a catalyst- lowers the energy of activation. Enzymes (proteins-very important in lowering the energy of activation).