Chem Ch. 1-5.1 definitions

Question 1

Theory

Answer 1

• Represents the best current explanation for a phenomenon, but it is always tentative.
• organizes scientific knowledge.

Question 2

Scientific law

Answer 2

• Large amounts of scientific data summarized in brief verbal or mathematical statements.
• A summary of experimental and/or observational data, often expressed in the form of a mathematical equation.

Question 3

Hypothesis

Answer 3

An educated guess.

Question 4

Model

Answer 4

• A design used to classify and organize information; a means for understanding nature.
• summarizes some aspects of what is being studied in a simplified fashion.

Question 5

Matter

Answer 5

The stuff that makes up all material things. It is anything that occupies space and has mass.

Question 6

Mass

Answer 6

• A measure of the quantity of matter that an object contains.
• Weight is a measurement of the force of attraction between two masses, usually one large one like Earth or the moon.

Question 7

Variable

Answer 7

Something that can change over the course of an experiment.

Question 8

Molecule

Answer 8

A group of atoms bound together as a single unit.

Question 9

Element

Answer 9

One of the fundamental substances from which all material things are constructed.

Cannot be broken down into simpler substances by any chemical process.

Question 10

Compound

Answer 10

A substance made up of two or more elements chemically combined in a fixed ratio.

Question 11

Chemical symbol

Answer 11

One or two letters derived from the name of the element. Each element can be represented by this.

Question 12

Atom

Answer 12

The smallest characteristic part of an element.

Question 13

Chemophobia

Answer 13

And unreasonable fear of chemicals.

Question 14

Kelvin (K)

K = *C + 273.15

Answer 14

The SI base unit of temperature.

Question 15

Paragigm

Answer 15

Final level of scientific conceptualization-a set of grand or all encompassing theories.

A distinct set of concepts or thought patterns, including theories research methods postulates and standards for what constitutes legitimate contributions to a field.

Question 15

Scientific Fact

Answer 15

Repeated observations that produce the same result every time.

Question 16

Chemical formula

Answer 16

The combination of elemental symbols used to describe a chemical compound. It consists of letters and where applicable subscript numbers.

Question 17

Mixture

Answer 17

Two or more pure substances combined with each other.

The composition of a mixture may vary from one part of the sample to another.

Question 18

Phase

Answer 18

The state that a specific amount of matter is in; it is usually solid, liquid or gas.

A physically distinctive form of matter such as a solid, liquid, gas or plasma.

Question 19

Celsius

Answer 19

Temperature scale used by the international system of units. Based on 0°C as the melting point of water and 100°C as the boiling point. Boiling point varies with altitude.

Question 20

Atomic mass units (amu)

Answer 20

Expressed in Atomic mass units, or just units.

Relative atomic weight based upon carbon-12.

Question 21

Electron

Answer 21

Negatively charged units.

Question 22

Proton

Answer 22

A unit that has a positive charge in the nucleus. Has a charge equal in magnitude to that of the electron.

Question 23

Neutron

Answer 23

A particle with about the same mass as a proton but with no electrical charge.

Neutral charge

Question 24

X-ray

Answer 24

A form of high electromagnetic radiation- energy with electric and magnetic components.

Question 25

Radioactivity

Answer 25

The spontaneous decomposition of unstable atomic nuclei.

Question 26

Nucleus

Answer 26

The positively charged central core of an Adam consisting of protons and neutrons and containing nearly all its mass.

Question 27

Atomic number

Answer 27

Number of protons in the nucleus. The atomic number identifies which element an atom is.

Question 28

Atomic weight

Answer 28

Determined by the statistical technique known as weighed average.

Question 29

Isotopes

Answer 29

Atoms with the same number of protons but different numbers of neutrons.

Question 30

Period

Answer 30

A horizontal row of elements in the periodic table.

Question 31

Group

Answer 31

A vertical column of elements in the periodic table.

Question 32

Noble gases

Answer 32

Non-chemically reactive, colorless gasses composed of single Atoms.

They are non-reactive because they possess an ideal number of electrons.

Question 33

Halogens

Answer 33

Diatomic molecules that readily form negatively charged components of salts.

Question 34

Alkali metals

Answer 34

Soft metals that do not exist in nature as free elements do to their reactivity; readily form positively charged components of salts.

Question 35

Alkaline earth metals

Answer 35

Harder, less reactive, elements than alkali metals; however, they react vigorously with oxygen.

Question 36

Transition metals

Answer 36

The metallic elements that serve as a bridge, or transition, between the two sides of the periodic table.

Can form colored compounds, commonly possesses different oxidation states, many can be magnetic, Have high densities- freezing and boiling points.

Question 37

Fluorescence

Answer 37

The glow given off by certain chemicals when exposed to strong sunlight.

Certain chemicals exhibit florescence after exposure to strong sunlight.

Question 38

Valence electron

Answer 38

Determine most of the chemistry of an atom. The name of that outermost shell of an atom. The group number tells us how many electrons are in the outer most shell.

Question 39

Carbon dating

Answer 39

Relatively accurate, can date back to 60-70,000 YBP. (Years before present)

Can address anything that has carbon in it from less than 70,000 YBP.

Question 40

Electromagnetic spectrum

Answer 40

Light Energy occurs across a continuum of wavelengths.

Question 41

Chemical equation

Answer 41

A notation system used to represent a chemical reaction. It consists of symbols for reaction species and product species separated by arrow (indicating the direction of the reaction).

Question 42

Chemical reaction

Answer 42

When some or all of the chemical bonds in the reactants are broken and new bonds are formed as the products are created.

Question 43

Coefficient

Answer 43

The number in front of the compound or molecule. Tells how many atoms are present.