Chptr 3 Vocab

Front 1

nucleus

Back 1

the central and most important part of an object, movement, or group, forming the basis for its activity and growth.

Front 2

atomic number

Back 2

the number of protons in the nucleus of an atom, which determines the chemical properties of an element and its place in the periodic table

Front 3

proton

Back 3

with a positive electric charge of +1e elementary charge and mass slightly less than that of a neutron. Protons and neutrons, each with masses of approximately one atomic mass unit, are collectively referred to as "nucleons

Front 4

isotop

Back 4

each of two or more forms of the same element that contain equal numbers of protons but different numbers of neutrons in their nuclei, and hence differ in relative atomic mass but not in chemical properties; in particular, a radioactive form of an element.

Front 5

neutron

Back 5

with no net electric charge and a mass slightly larger than that of a proton. Protons and neutrons, each with mass approximately one atomic mass unit, constitute the nucleus of an atom, and they are collectively referred to as nucleons. Their properties and interactions are described by nuclear physics.

Front 6

mass number

Back 6

the total number of protons and neutrons in a nucleus.

Front 7

electron

Back 7

he electron is a subatomic particle with a negative elementary electric charge.

Front 8

model

Back 8

Model (product), an identifier of a product given by its manufacturer (also calledmodel number)

Front 9

atomic mass

Back 9

he mass of an atom of a chemical element expressed in atomic mass units. It is approximately equivalent to the number of protons and neutrons in the atom (the mass number) or to the average number allowing for the relative abundances of different isotopes.

Front 10

period

Back 10

A period is the name given to a horizontal row of the periodic table. The periodic table has seven periods. Period 1 contains only two elements: hydrogen and helium.

Front 11

periodic table

Back 11

a table of the chemical elements arranged in order of atomic number, usually in rows, so that elements with similar atomic structure (and hence similar chemical properties) appear in vertical columns.

Front 12

group

Back 12

control group. noun. The control group is defined as the group in an experiment or study that does not receive treatment by the researchers and is then used as a benchmark to measure how the other tested subjects do

Front 13

chemical symbol

Back 13

chemical symbol. noun. an abbreviation or short representation of a chemicalelement; the symbols in the periodic table. Natural elements all have chemical symbols of one or two letters; some manmade elements have three-letter symbols

Front 14

metal

Back 14

a solid material that is typically hard, shiny, malleable, fusible, and ductile, with good electrical and thermal conductivity (e.g., iron, gold, silver, copper, and aluminum, and alloys such as brass and steel).

Front 15

malleable

Back 15

(of a metal or other material) able to be hammered or pressed permanently out of shape without breaking or cracking.

Front 16

ductile

Back 16

(of a metal) able to be drawn out into a thin wire.

Front 17

conductivity

Back 17

the degree to which a specified material conducts electricity, calculated as the ratio of the current density in the material to the electric field that causes the flow of current. It is the reciprocal of the resistivity

Front 18

reactivuty

Back 18

the state or power of being reactive or the degree to which a thing is reactive.

Front 19

corrision

Back 19

the process of corroding metal, stone, or other materials

Front 20

alkali matal

Back 20

any of the elements lithium, sodium, potassium, rubidium, cesium, and francium, occupying Group IA (1) of the periodic table. They are very reactive, electropositive, monovalent metals forming strongly alkaline hydroxides

Front 21

alikine earth metal

Back 21

any of the elements beryllium, magnesium, calcium, strontium, barium, and radium, occupying Group IIA (2) of the periodic table. They are reactive, electropositive, divalent metals, and form basic oxides that react with water to form comparatively insoluble hydroxides.

Front 22

transition metal

Back 22

The 38 elements in groups 3 through 12 of the periodic table are called "transition metals". As with all metals, the transition elements are both ductile and malleable, and conduct electricity and heat.

Front 23

alloy

Back 23

a metal made by combining two or more metallic elements, especially to give greater strength or resistance to corrosion.

Front 24

particle accelerater

Back 24

A particle accelerator is a machine that accelerates elementary particles, such as electrons or protons, to very high energies. Whether it's medical or scientific research, consumer product development or national security,particle accelerators touch nearly every part of our daily lives

Front 25

nonmetal

Back 25

an element or substance that is not a metal.

Front 26

noble gas

Back 26

any of the gaseous elements helium, neon, argon, krypton, xenon, and radon, occupying Group 0 (18) of the periodic table. They were long believed to be totally unreactive but compounds of xenon, krypton, and radon are now known.

Front 27

diatomic molecule

Back 27

Diatomic molecules are molecules composed of only two atoms, of the same or different chemical elements. The prefix di- is of Greek origin, meaning "two". If a diatomic molecule consists of two atoms of the same element, such as hydrogen (H2) or oxygen (O2), then it is said to be homonuclear.

Front 28

mettaloid

Back 28

an element (e.g., germanium or silicon) whose properties are intermediate between those of metals and solid nonmetals. They are electrical semiconductors.

Front 29

halgen

Back 29

any of the elements fluorine, chlorine, bromine, iodine, and astatine, occupying group VIIA (17) of the periodic table. They are reactive nonmetallic elements that form strongly acidic compounds with hydrogen, from which simple salts can be made.

Front 30

semi conducter

Back 30

a solid substance that has a conductivity between that of an insulator and that of most metals, either due to the addition of an impurity or because of temperature effects. Devices made of semiconductors, notably silicon, are essential components of most electronic circuits.