Chapter 2

Matter

Anything that has mass and takes up space

Mass

the amount of matter in an object

weight

the force of gravity on an object

Element

A pure substance made of only one kind of atom

Atom

is the smallest particle of an element that has the chemical characteristics of that element.

The four elements that make up about 96% of body weight are \________.

Carbon, hydrogen, oxygen and nitrogen.
Oxygen is the most abundant element in our body.

Neutron

A subatomic particle that has no charge and that is found in the nucleus of an atom

Proton

A subatomic particle that has a positive charge and that is found in the nucleus of an atom

Electron

A subatomic particle that has a negative charge. The electrons are found in an electron cloud and are constantly orbiting the nucleus

what is the atomic number equal to?

number of protons and electrons (electrons \= protons)

mass number

is the number of protons plus the number of neutrons in each atom. For example, the mass number for carbon is 12 because it has 6 protons and 6 neutrons.

isotope

are two or more forms of the same element that have the same number of protons and electrons but a different number of neutrons. Thus, isotopes have the same atomic number but different mass numbers.

atomic mass

is the average mass of its naturally occurring isotopes, taking into account the relative abundance of each isotope.

Avogadro's number or 1 mole

number of representative particles in a mole, 6.02 X 10^23

mollar mass

The mass of 1 mole of a substance expressed in grams. Molar mass is a convenient way to determine the number of atoms in a sample of an element.

valence shell

The outermost energy shell of an atom, containing the valence electrons involved in the chemical reactions of that atom.

octet rule

States that atoms lose, gain or share electrons in order to acquire a full set of eight valence electrons

Cation

A positively charged ion

Aions

negatively charged ions

ionic bond

A chemical bond resulting from the attraction between oppositely charged ions.
A sodium atom (Na) loses an electron to become a smaller, positively charged ion, and a chlorine atom (Cl) gains an electron to become a larger, negatively charged ion. The attraction between the oppositely charged ions results in ionic bonding and the formation of sodium chloride.

covalent bond

A chemical bond that involves sharing a pair of electrons between atoms in a molecule
Five examples of covalent bonds are hydrogen (H₂), oxygen (O₂), nitrogen (N₂), water (H₂O), and methane(CH₄)

polar covalent bond

A covalent bond in which electrons are not shared equally

non polar covalent bond

a covalent bond in which the bonding electrons are shared equally by the bonded atoms, resulting in a balanced distribution of electrical charge.

single covalent bond

two atoms held together by sharing one pair of electrons

double covalent bond

a bond in which two atoms share two pairs of electrons

triple covalent bond

a covalent bond in which three pairs of electrons are shared by two atoms

Molecule

two or more atoms chemically bonded together to form a structure.

Compound

is a substance resulting from the chemical combination of two or more different types of atoms. Water is a molecule that is also a compound because it is a combination of two different atoms, hydrogen and oxygen. But not all molecules are compounds. For example, a hydrogen molecule is not a compound because it does not consist of different types of atoms.

How do you find molar mass

adding up the atomic masses of its atoms (or ions). The term molecular mass is used for convenience for ionic compounds, even though they are not molecules. For example, the atomic mass of sodium is 22.99 and that of chloride is 35.45. The molecular mass of NaCl is therefore 58.44 (22.99 + 35.45).

intermolecular forces

the weak electrostatic attractions that exist between oppositely charged parts of molecules, or between ions and molecules. There is no exchange of electrons in intermolecular forces. This differs from other chemical bonds. Intermolecular forces are much weaker than the forces producing chemical bonding. Intermolecular forces include hydrogen bonds and the properties of solubility and dissociation.

hydrogen bond

A type of weak chemical bond formed when the slightly positive hydrogen atom of a polar covalent bond in one molecule is attracted to the slightly negative atom of a polar covalent bond in another molecule. For example, in water molecules (H2O), hydrogen is covalently bonded to the more electronegative oxygen atom. Therefore, hydrogen bonding arises in water molecules due to the dipole-dipole interactions between the hydrogen atom of one water molecule and the oxygen atom of another H2O molecule.

Solubility

is the ability of one substance to dissolve in another—for example, sugar dissolving in water. Charged substances, such as sodium chloride, and polar substances, such as glucose, readily dissolve in water, whereas nonpolar substances, such as oils, do not

Dissociation

the separation of ions that occurs when an ionic compound dissolves

Electrolyte

Cation or anion in solution that conducts an electric current.Electrolytes are essential for basic life functioning, such as maintaining electrical neutrality in cells and generating and conducting action potentials in the nerves and muscles. Significant electrolytes include sodium, potassium, chloride, magnesium, calcium, phosphate, and bicarbonates.

synthesis reaction

is when two or more reactants chemically combine to form a new and larger product. The collective term for synthesis reactions in the body is anabolism (an-AB-oh-lizm). These reactions produce the molecules characteristic of life, such as ATP, proteins, carbohydrates, lipids, and nucleic acids. The growth, maintenance, and repair of the body could not take place without anabolic reactions.

synthesis/dehydration reaction

Water is removed from the chemical reaction to synthesis or form biomolecules or polymers

Decompotion reaction

is the reverse of a synthesis reaction—a larger reactant is chemically broken down into two or more smaller products. The decomposition reactions occurring in the body are collectively called catabolism (kah-TAB-oh-lizm). They include the digestion of food molecules in the intestine and within cells, the breakdown of stored lipids, and the breakdown of foreign matter and microorganisms in certain blood cells that protect the body. All of the anabolic and catabolic reactions in the body are collectively defined as metabolism.

reversible reaction

is when the reaction can run in the opposite direction, so that the products are converted back to the original reactants.

Oxidation

The loss of an electron by an atom

reduction

gain of electrons

energy

The ability to do work or cause change

potential energy

Energy in a chemical bond that is not being exerted or used to do work.

kinetic energy

Motion energy or energy that can do work.

mechanical energy

Kinetic or potential energy associated with the motion or position of an object

chemical energy

A form of potential energy that is stored in chemical bonds between atoms.

heat energy

a form of energy that is transferred by a difference in temperature

activation energy

Energy that must be added to molecules to initiate a reaction.

How do enzymes lower activation energy?

Enzymes generally lower activation energy by reducing the energy needed for reactants to come together and react. For example: Enzymes bring reactants together so they don't have to expend energy moving about until they collide at random.

catalyst

Substance that increases the rate at which a chemical reaction proceeds without being changed permanently.

inorganic chemistry

generally deals with substances that do not contain carbon, although a more rigorous definition is the lack of carbon-hydrogen bonds.

organic chemistry

is the study of carbon-containing substances, with a few exceptions. For example, carbon monoxide (CO), CO2, and bicarbonate ions (HCO3−) are several important inorganic substances that contain carbon but lack C—H bonds.

five important inorganic molecules we need for life

(1) O2 we breathe, (2) CO2 we exhale, (3) water essential for life, (4) calcium phosphate that makes up our bones, and (5) metals required for protein functions, ranging from iron in blood gas transport to zinc in alcohol detoxification.

What are the 4 important functions that water performs in the body?

stabilize body temp, protection, chemical reactions, and mixing medium

Choesion

attraction of water to another water molecule. Examples of cohesion are the surface tension exhibited when water bulges over the top of a full glass without spilling over and when beads of water form on the skin.

Adhesion

attraction of water to other molecules. An example of adhesion is the surface tension that draws water across a glass plate and holds a bead of water to the skin before it falls to the ground. For both cohesion and adhesion, the attractive force is hydrogen bonds. The combination of cohesion and adhesion helps hold cells together and move fluids through the body.

Mixture

is a combination of two or more substances physically blended together, but not chemically combined

Solution

is any mixture in which the substances are uniformly distributed. Solutions can be liquid, gas, or solid. For example, a salt solution consists of salt dissolved in water, air is a solution containing a variety of gases, and wax is a solid solution composed of several fatty substances.

Solute

A substance that is dissolved in a solution.

Solvent

the substance in which the solute dissolves

Suspension

Liquid through which a solid is dispersed and from which the solid separates unless the liquid is kept in motion.
a mixture containing materials that separate from each other unless they are continually, physically blended together. Blood is a suspension—that is, red blood cells are suspended in a liquid called plasma. As long as the red blood cells and plasma are mixed together as they pass through blood vessels, the red blood cells remain suspended in the plasma. However, if the blood is allowed to sit in a container, the red blood cells and plasma separate from each other.

Colloid

a mixture in which a dispersed substance or particle is unevenly distributed throughout the mixture. Unlike a suspension, the dispersed particles are small enough that they do not settle out. Proteins are common dispersed particles; proteins and water form colloids. For instance, the plasma portion of blood and the liquid interior of cells are colloids containing many important proteins.

Acid

Molecule that is a proton donor; any substance that releases hydrogen ions (H+).

base

Molecule that is a proton acceptor; any substance that binds to hydrogen ions. Lower part or bottom of a structure; the base of the heart is the flat portion directed posteriorly and superiorly; veins and arteries project into and out of the base, respectively.

What is a molecule called that releases H+?

Acid

What is meant by a strong or weak acid/base?

Any acid that dissociates 100% into ions is called a strong acid. If it does not dissociate 100%, it is a weak acid.

pH scale

Acidosis

Acidosis results if blood pH drops below 7.35. In this case, the nervous system becomes depressed and the individual may become disoriented and possibly comatose.

Alkalosis

Alkalosis results if blood pH rises above 7.45. In this case, the nervous system becomes overexcitable, and the individual may become extremely nervous or have convulsions. Both acidosis and alkalosis can be fatal.

Normal pH of blood

The normal pH range for human blood is 7.35 to 7.45

Salt

A salt is a compound consisting of a cation other than H+ and an anion other than OH−.

How are salts formed?

Salts are formed by the interaction of an acid and a base in which the H+ of the acid are replaced by the positive ions of the base. For example, in a solution in which hydrochloric acid (HCl) reacts with the base sodium hydroxide (NaOH), the salt sodium chloride (NaCl) is formed:

Buffer

chemicals that resist changes in pH when either acids or bases are added to a solution. For example, when an acid is added to a buffered solution, the buffer binds to the H+, preventing these ions from causing a decrease in the pH of the solution

What are the four essential molecules to living things?

carbohydrates, lipids, proteins, and nucleic acids

Carbohydrates

organic molecules composed primarily of carbon, hydrogen, and oxygen atoms and range in size from small to very large.

What three roles do carbohydrates play in the human body?

(1) They are parts of other organic molecules, (2) they are broken down to provide energy, and (3) when undigested they provide bulk in feces.

Monosaccharides

Simple sugar carbohydrate that cannot form any simpler sugar by hydrolysis.
Monosaccharides commonly contain 3 carbons (trioses), 4 carbons (tetroses), 5 carbons (pentoses), or 6 carbons (hexoses).

Disaccharide

Condensation product of two monosaccharides by the elimination of water.
For example, glucose and fructose combine to form a disaccharide called sucrose (table sugar) plus a molecule of water. In addition to sucrose, two other disaccharides important to humans are lactose and maltose.

Polysaccharides

Carbohydrate containing a large number of monosaccharide molecules.
Three important polysaccharides are glycogen, starch, and cellulose.

Isomers

Molecules having the same number and types of atoms but differing in their three-dimensional arrangement.
Common 6-carbon sugars, such as glucose, fructose, and galactose, are isomers

Glycogen

Glycogen, or animal starch, is a multibranched polysaccharide composed of many glucose molecules. Glycogen is the main storage form of glucose in humans.

Starch/cellulose

Starch and cellulose are two important polysaccharides found in plants. Like glycogen, both are composed of long chains of glucose. Starch is an energy-storage molecule in plants, similar to the role of glycogen in animals. Cellulose is an important structural component of plant cell walls. When humans ingest plants, the starch can be broken down and used as an energy source. Humans, however, do not have the digestive enzymes necessary to break down cellulose. Cellulose is eliminated in the feces, where it provides bulk. Clinically, the presence of cellulose (fiber) in our diet is important for regularity of bowel movements and has been reported to help reduce cholesterol and control blood sugar levels.

Lipids

Substance composed principally of carbon, oxygen, and hydrogen; contains a lower ratio of oxygen to carbon and is less polar than carbohydrates; generally soluble in nonpolar solvents.

Lipids main role in body

They (1) provide protection and insulation, (2) help regulate many physiological processes, (3) form plasma membranes, and (4) act as major energy-storage molecules.

What is a lipid made up of?

Like carbohydrates, lipids are composed principally of carbon, hydrogen, and oxygen, but lipids have a lower ratio of oxygen to carbon than do carbohydrates. This makes them less polar.

What can lipids dissolve in?

lipids can be readily dissolved in nonpolar organic solvents, such as alcohol or acetone, but they are relatively insoluble in water. Some lipids also contain small amounts of other elements, such as phosphorus and nitrogen, which can aid solubility in water.

The five major classes of lipids are

(1) fats, which are mostly triglycerides; (2) phospholipids; (3) eicosanoids; (4) steroids; and (5) fat-soluble vitamins.

Adipose

Adipose tissue is a specialized connective tissue consisting of lipid-rich cells called adipocytes. As it comprises about 20-25% of total body weight in healthy individuals, the main function of adipose tissue is to store energy in the form of lipids (fat).

Triglycerides

Three-carbon glycerol molecule with a fatty acid attached to each carbon; constitutes approximately 95% of the fats in the human body. Also called triacylglycerol.
Triglycerides consist of two different types of building blocks: (1) one glycerol and (2) three fatty acids.

saturated fatty acid

Fatty acid in which the carbon chain contains only single bonds between carbon atoms.
Sources of saturated fats include beef, pork, whole milk, cheese, butter, eggs, coconut oil, and palm oil.

unsaturated fatty acid

Carbon chain of a fatty acid that possesses one or more double or triple bonds.
Unsaturated fats:
Olive, peanut, and canola oils.
Avocados.
Nuts such as almonds, hazelnuts, and pecans.
Seeds such as pumpkin and sesame seeds.

monounsaturated fats

such as olive and peanut oils, have one double covalent bond between carbon atoms.

polyunsaturated fats

such as safflower, sunflower, corn, and fish oils, have two or more double covalent bonds between carbon atoms. Unsaturated fats are the best type of fats in the diet because, unlike saturated fats, they do not contribute to the development of cardiovascular disease.

trans fat

unsaturated fats that have been chemically altered by the addition of hydrogen. The process makes the fats more saturated and hence more solid and stable (longer shelf life). However, the double covalent bonds that do not become saturated are changed from the usual cis configuration (H on the same side of the double bond) to a trans configuration (H on different sides). This change in structure makes the consumption of trans fats an even greater factor than saturated fats in the risk for cardiovascular disease.

Choesterol

is a steroid hormone. It is the backbone of all your hormones of your body. Without cholesterol you do not make things like estrogen and testosterone.

Protein

Macromolecule consisting of long sequences of amino acids linked together by peptide bonds. contain carbon, hydrogen, oxygen, and nitrogen bound together by covalent bonds. Most proteins also contain some sulfur. In addition, some proteins contain small amounts of phosphorus, iron, and iodine.

five important functions of proteins

(1) regulate body processes, (2) act as transportation molecules, (3) provide protection, (4) help muscles contract, and (5) provide structure and energy.

Basic building blocks of proteins

The basic building blocks for proteins are the 20 amino acid molecules. Each amino acid has an amine group (—NH2), a carboxyl group (—COOH), a hydrogen atom, and a side chain designated by the symbol R attached to the same carbon atom. The side chain can be a variety of chemical structures, and the differences in the side chains make the amino acids different from one another.

peptide bond

Covalent bonds formed between amino acid molecules during protein synthesis

Dipeptide

two amino acids bound together by a peptide bond

tripeptide

three amino acids covalently bound together by peptide bonds