Chapter 3

Question 1

Atom

Answer 1

In modern terms, an atom is the smallest particle that can still considered a element.

Question 2

Electron

Answer 2

In 1897, J.J. Thomas discovered that atoms contain negatively charged particles called electrons.

Question 3

Nucleus

Answer 3

So Rutherford inferred that an atom’s positive charge must be packed within a small region in its center, called nucleus.

Question 4

Proton

Answer 4

Rutherford called the positively charged particles in an atom’s nucleus protons.

Question 5

Energy Level

Answer 5

An electron’s movement is related to its energy level, or the specific amount of energy it has.

Question 6

Neutron

Answer 6

This particle, called a neutron, was hard to find because it has no electric charge.

Question 7

Atomic Number

Answer 7

The number of protons in the nucleus of an atom is the atomic number of that atom’s element.

Question 8

Mass Number

Answer 8

A isotope is identified by its mass number, which is the sum of the protons and neutrons in a atom.

Question 9

Isotope

Answer 9

Atoms with the same number of protons and different numbers of neutron are called isotopes.

Question 10

Atomic Mass

Answer 10

The atomic mass of an element is the average mass of all the isotopes of that element.

Question 11

Periodic Table

Answer 11

A periodic table is an arrangement of elements showing the repeating pattern of their properties.

Question 12

Chemical Symbol

Answer 12

Chemical symbols contain either one or two letters below the atomic number.

Question 13

Periods

Answer 13

The periodic table is arranged in rows called periods.

Question 14

Group

Answer 14

The elements in a column form a group.

Question 15

Metal

Answer 15

Metals are elements that are good conductors of electric current and heat.

Question 16

Luster

Answer 16

A material that has high luster is shiny and reflective.

Question 17

Malleable

Answer 17

A malleable material is one that can be hammered or rolled into flat sheets or other shapes.

Question 18

Ductile

Answer 18

A ductile material is one that can be pulled out, or drawn, into long wires.

Question 19

Thermal Conductivity

Answer 19

Thermal Conductivity is the ability of an object to transfer heat.

Question 20

Electrical Conductivity

Answer 20

Electrical Conductivity is the ability of an object to carry electric current.

Question 21

Reactivity

Answer 21

The ease and speed with which an element combines, or reacts, with other substances is called its reactivity.

Question 22

Corrosion

Answer 22

The deterioration of a metal due to a chemical reaction in the environment is called corrosion.

Question 23

Alkali Metal

Answer 23

The metals of Group 1, from lithium to francium are called alkali metals. These metals are the most reactive metals in the periodic table.

Question 24

Alkaline Earth Metal

Answer 24

The metals of Group 2 are called the alkaline earth metals. These metals are harder and denser, and melt at higher temperatures than the alkali metals.

Question 25

Transition Metal

Answer 25

The elements in Group 3 through 12 are called transition metals. The transition metals include iron, copper, gold, nickel and sliver. Most of these metals are hard and shiny solids.

Question 26

Nonmetal

Answer 26

A nonmetal is an element that asks most of the properties of a metal.

Question 27

Diatomic Molecule

Answer 27

A diatomic molecule is made up of two atoms.

Question 28

Halogen

Answer 28

Group 17 contains nonmetals fluorine, chlorine, bromine, and iodine. These elements are also known the halogens,which means “ salt forming”

Question 29

Noble Gas

Answer 29

The elements in group 18 are known as the noble gases. They do not ordinarily form compounds because atoms of noble gases do not usually gain, lose, or share electrons.

Question 30

Metalloid

Answer 30

The metalloids have some properties of metals and some properties of nonmetals.

Question 31

Semiconductor

Answer 31

Semiconductors are substances that can conduct electric current under some conditions but not under other conditions.

Question 32

Radioactive decay

Answer 32

In a process called radioactive decay, the atomic nuclei of radioactive isotopes release fast-moving particles and energy.

Question 33

Nuclear reaction

Answer 33

Nuclear reactions involve the particles in the nucleus of an atom.

Question 34

Radioactivity

Answer 34

The uranium was able to spontaneously emit radiation. Marie Curie called this property radioactivity

Question 35

Alpha particle

Answer 35

An alpha particle consists of two protons and two neutrons. It is positively charged

Question 36

Beta particle

Answer 36

A beta particle is a fast-moving electron given off by a nucleus during radioactive decay.

Question 37

Gamma ray

Answer 37

Gamma rays consist of high-energy waves, simular to x-rays. gamma rays have no charge.

Question 38

Half-life

Answer 38

The half-life of a radioactive isotope is the length of time needed for half of the atoms of a sample to decay.

Question 39

Radioactive dating

Answer 39

Scientists can calculate how many half-lives have passed since the plant died and estimate the age of the fossil. This process is called radioactive dating

Question 40

Tracer

Answer 40

Tracers are radioactive isotopes that can be followed through the steps of a chemical reaction or an industrial process.