APES - Chapter 2

system

A set of interacting components connected in such a way that a change in one part of the system affects one or more other parts of a system

matter

anything that occupies space and has mass.

mass

a measure of the amount of matter an object contains.

weight

the force that results from the action of gravity on mass.

atom

the smallest particle that can contain the chemical properties of an element.

element

a substance composed of atoms that cannot be broken down into smaller, simpler components. Elements can be solid, liquid or gas.

periodic table

lists all the elements currently known.

molecules

particles containing more than one atom.

compounds

molecules that contain more than one element.

atomic number

the number of protons in the nucleus of a particular element.

mass number

the total number of protons and neutrons in an element.

isotopes

atoms of the same element that have different numbers of neutrons, and therefore different atomic masses.

Radioactive decay

the spontaneous release of material from the nucleus of an unstable isotope.

changes

Radioactive decay _______ the radioactive element into a different element

half-life

the time it takes for one-half of the original radioactive parent atoms to decay.

emit

Some elements that undergo radioactive decay ____ harmful radiation.

length

Knowledge of the half-life allows scientists to determine the _____ of time that a radioactive element may be dangerous.

Covalent bonds

elements that form compounds by sharing electrons.

Ionic bonds

elements that form compounds by transferring electrons from one element to another.

positively, negatively

in an ionic bond, one atom becomes electron deficient (_____ charged) and one atom becomes electron rich (_______ charged)

Hydrogen bonds-

A weak chemical bond that forms when hydrogen atoms that are covalently bonded to one atom are attracted to another atom on another molecule

one side is more positive and the other side is more negative

Why is a water molecule polar

Surface tension

the result form the cohesion of water molecules at the surface of a body of water

Capillary action

when adhesion of water molecules to a surface is stronger than cohesion between the molecules

Boiling and freezing

at Earth’s surface, water boils at 100 degrees celsius and freezes at 0 degrees celsius.

Water as a solvent

many substances dissolve well in water because their polar molecules bond easily with other polar molecules

Acid

a substance that contributes hydrogen ions to a solution.

Base

a substance that contributes hydroxide ions to a solution.

Basic

7.1-14

Acidic

0-6.9

Chemical reaction

occurs when atoms separate from the molecules they are a part of or recombine with other molecules.

Law of conservation of matter

matter cannot be created or destroyed; it can only change form

Inorganic compounds

compounds that do not contain carbon or do contain carbon, but only carbon bound to elements other than hydrogen.

Organic compounds

compounds that have carbon-carbon and carbon-hydrogen bonds.

Carbohydrates

compounds composed of carbon, hydrogen, and oxygen atoms.

Proteins

made up of long chains of nitrogen-containing organic molecules called amino acids.

Nucleic Acids

organic compounds found in all living cells

Lipids

smaller biological molecules that do not mix with water.

Cells

the smallest structural and functional component of organisms.

energy

the ability to do work

power

the rate at which work is done

Kinetic energy

energy of motion

Potential energy

energy that is stored

chemical energy

potential stored in chemical bonds

Temperature

the measure of the average kinetic energy of a substance.

energy is neither created nor destroyed

first law of thermodynamics

second law of thermodynamics

When energy is transformed, the quantity of energy remains the same, but its ability to do work diminishes.

Energy Efficiency

the ratio of the amount of work that is done to the total amount of energy that is introduced into the system.

Energy quality

the ease with which an energy source can be used for work

Entropy

all systems move toward randomness rather than toward order

Open system

exchanges of matter or energy occur across system boundaries

Closed system

matter and energy exchanges across system boundaries do not occur (Earth)

Steady state

in a system, when input equals output it is said to be in a steady state.

Negative feedback loops

when a system responds to change by returning to its original state, or at least by decreasing the rate at which the change is occurring

Positive feedback loops

when a system responds to change by increasing the rate at which the change is occurring