Chapter 2: Chemistry of Life

Endothermic

An endothermic reaction absorbs more energy than it releases

Exothermic

An exothermic chemical reaction releases more energy than it absorbs

Why does an ion form?

An ion forms because an atom is more stable when its outermost energy shell is full; the gain or loss of electrons results in a full outermost energy level.

Carbon, hydrogen, and oxygen are my building blocks; sometimes I am broken down as a source of energy, and sometimes I make up plant cell walls.

carbohydrate

1. substances that decreases activation energy 2. increases rate of a chemical reaction

catalyst

Chemical Reaction

changes substances into different substances by breaking and forming chemical bonds

Which property causes water to form beads?

cohesion

Chemical bonds hold me together; I always contain atoms of more than one element.

compound

Base

compound that removes hydrogen ions from a solution

Water and Carbon Dioxide, are examples of what?

compounds

A molecule is held together by _____.

covalent bonds

Nucleus

dense center of an atom

Monomer

each smaller molecule is a subunit called this

Two atoms may form several covalent bonds to share several pairs of ___.

electrons

What is made up of only one type of atom?

elements

1. reactants have greater bond energy than products 2. photosynthesis

endothermic

I am a chemical reaction that absorbs more energy than I release; my products have a higher bond energy than my reactants.

endothermic

I allow chemical reactions to take place under the tightly controlled conditions in living things; in almost all cases I am a protein.

enzyme

A solution is a mixture of substances that is __ distributed throughout the entire mixture.

evenly

Equilibrium EXAMPLE:

evenly matched tug-of-war

Polar molecules have two regions with a slight positive charge.

false; to make it true, add " and a slight negative charge" to the end of the statement.

I am a carbon chain found in many lipids; I can be either saturated or unsaturated.

fatty acid

Ionic Bond

forms through the electrical force between oppositely charged ions

Covalent Bond

forms when atoms share a pair of electrons

Solute EXAMPLE:

getting lost in a crowd

Which property allows water to resist changes in temperature?

high specific heat

I am an attraction between a slightly positive hydrogen atom and a slightly negative atom, such as oxygen or nitrogen.

hydrogen bond

1. atom that has gained or lost electrons 2. results in a full outermost energy level

ion

I have a positive charge if I lose an electron, or I have a negative charge if I gain an electron.

ion

Acid

is a compound that releases a proton - a hydrogen ion - when it dissolves in water

Solution

is a mixture of substances that is the same throughout - it is a homogeneous mixture

Polymer

is a molecule that contains many monomers bonded together

Protein

is a polymer made of monomers called amino acids

Compound

is a substance made of atoms of different elements, bonded together in a certain ratio

Catalyst

is a substance that decreases the activation energy needed to start a chemical reaction, and, as a result, also increases the rate of the chemical reaction

Solute

is a substance that dissolves in a solvent

Ion

is an atom that has gained or lost one or more electrons

Hydrogen Bond

is an attraction between a slightly positive hydrogen atom and a slightly negative atom

Element

is one particular type of atom, and it cannot be broken down into a simpler substance by ordinary chemical means

Activation Energy

is the amount of energy that needs to be absorbed for a chemical reaction to start

Bond Energy

is the amount of energy that will break a bond between two atoms

Atom

is the smallest basic unit of matter

Solvent

is the substance that is present in greater amounts and that dissolves another substance

Molecule

is two or more atoms held together by covalent bonds

Activation Energy EXAMPLE:

kick-starting a motor cycle

Covalent Bond EXAMPLE:

linking hands in a human chain

1. held together by covalent bonds 2. can be of the same element

molecule

I am held together by covalent bonds; I can be made of atoms of just one element.

molecule

"Oil and water don't mix" because a ___ molecule can't easily dissolve in a polar solvent.

nonpolar

I am the type of molecule that stores genetic information in living things; I include DNA and RNA.

nucleic acid

Amino Acid EXAMPLE:

one of many beads on a string

Shared pairs of electrons fill the ___ energy levels of bonded atoms.

outermost

I measure the hydrogen ion concentration in a solution; when I am low a solution is very acidic.

pH

Electron

particle with a negative charge

Proton

particle with a positive charge

Neutron

particle with no electrical charge

Ionic Bond EXAMPLE:

passing a basketball

Many different types of me have many different functions in living things; I am made of amino acids.

protein

1. enters a chemical reaction 2. thing that is changed during a chemical reaction

reactant

A ___ dissolves in a solution.

solute

Blood plasma is an example of a ___.

solute

I am a certain type of mixture; I am formed when one substance, such as water, dissolves other substances.

solution

1. dissovles a solute 2. substance that is present in greater amounts

solvent

Covalent bonds are generally very ____.

strong

I am a reactant an enzyme acts on; I bind to an enzyme's active site.

substrate

Atom

the smallest basic unit of matter

Equilibrium

When a reaction takes place at an equal rate in both directions, the reactant and product concentrations stay the same

On the pH table, which side is more acidic. more basic, and which pH is neutral?

1 2 3 4 5 6 7 8 9 10 11 12 13 14 < more acidic more basic > The pH 7 is neutral

Carbohydrates

Carbohydrates are molecules composed of carbon, hydrogen, and oxygen, and they include sugars and starches. Carbohydrates can be broken down to provide a source of usable energy for cells. Carbohydrates are also a major part of plant cell structure. The most basic carbohydrates are simple sugars, or monosaccharides. many simple sugars have either five or six carbon atoms. Fruits contain a six carbon sugar called fructose, Glucose, one of the sugars made by plant cells during photosynthesis, is another six carbon sugar. Simple sugars can be bonded to make larger carbohydrates. Starches, glycogen, and cellulose are polysaccharaides.

High Specific Heat

Hydrogen bonds give water an abnormally high specific heat. This means that water resists changes in temperature. Compared ti many other compounds, water must absorb more heat energy to increase in temperature. This property is very important to cells. The processes that produce usable chemical energy in cells release a great deal of heat. Water absorbs the heat, which helps regulate cell temperatures.

Nucleic Acid

Nucleic acids are polymers that are made up of monomers called nucleotides. The two general types are: DNA and RNA

Cohesion

The attraction among molecules of a substance is cohesion. Cohesion from hydrogen bonds makes water molecules stick to each other. You can see this when water forms beads, such as on a recently washed car. Cohesion also produces surface tension, which makes a kind of skin on water.

Adhesion

The attraction among molecules of different substances is called adhesion. In other words, water molecules stick to other things. Adhesion is responsible for the upward curve on the surface of the water because water molecules are attracted to the glass of the test tube in figure 2.3. Adhesion helps plants transport water from their roots to their leaves because water molecules stick to the sides o the vessels that carry water.

1. includes sugars and starches 2. sometimes is broken down as an energy source

carbohydrate

Substrate

The specific reactants that an enzyme acts on is called this

Some ions are positively charged, and some ions have no charge.

This is false, To make this statement true, change "no charge" with "negative charge".

An atom becomes an ion when its number of protons changes.

This is false. To make it true, change "protons" with "electrons".

Ions usually form when electrons are transferred from one atom to another.

This statement is true.

The formation of an ion results in a full outermost energy level.

This statement is true.

Ionic Bond

a bond formed by the electrical force between two ions of opposite charge

Covalent Bond

a bond formed when two atoms share a pair of electrons

Lipid EXAMPLE:

a car's gas tank

Element

a particular type of atom

pH

a solution's acidity, or hydrogen ion concentration, is measured by this scale

Compound

a substance made of atoms of different elements bonded together in a certain ratio

1. releases hydrogen ion into a solution 2. increases the concentration of hydrogen ion in a solution

acid

I am the amount of energy that is needed for a chemical reaction to start; after I am added, the reaction can take place on it's own.

activation energy

Which property of water helps plants transport water from their roots to their leaves?

adhesion

Enzymes

are catalysts for chemical reactions in living things

Fatty Acid

are chains of carbon atoms bonded to hydrogen atoms

Amino Acids

are molecules that contain carbon, hydrogen, oxygen, nitrogen, and sometimes sulfur. Organisms use 20 different amino acids to build proteins. Your body can make 12 of the amino acids, the rest comes from foods that you eat such as meat, beans, nuts.

Lipid

are nonpolar molecules that include fats, oils, and cholesterol. Like carbohydrates, most lipids contain chains of carbon atoms bonded to oxygen and hydrogen atoms. Some lipids are broken down as a source of usable energy for cells. Other lipids are part of a cell's structure. Fats and oils store large amounts of chemical energy in organisms. They both consist of molecule called glycerol bonded to molecules called fatty acids.

Products

are the substances made by a chemical reaction

Reactants

are the substances that are changed during a chemical reaction

1.smallest basic unit of matter 2.contains protons, neutrons, and electrons

atom

I am the amount of energy needed to break a chemical bond; I am also the amount of energy released when a bond forms.

bond energy

Slightly charged regions of water molecules form hydrogen bonds.

true

Water is a polar molecule.

true

Molecule

two or more atoms held together by covalent bonds

Atom EXAMPLE:

unicellular organism