Matter Vocabulary

Question 1

atom

Answer 1

• definition: the smallest part of an element
• context: An atom is too small to see, so models are used to explain them.

Question 2

atomic number

Answer 2

• definition: the number of protons in the nucleus of each atom of an element
• context: On the periodic table, the elements are listed by atomic number.

Question 3

atomic mass

Answer 3

• definition: the mass of an element; nearly equal to the number of protons and neutrons found in the element’s nucleus
• context: The atomic mass of sodium is 22.990.

Question 4

chemical property

Answer 4

• definition: a characteristic of a substance that allows it to change to a new substance
• context: A chemical property of iron is that it reacts with oxygen in the air and produces rust.

Question 5

electron

Answer 5

• definition: an invisible, negatively charged particle that travels around the nucleus of an atom
• context: Electrons orbit the nucleus of an atom.

Question 6

electron cloud

Answer 6

• definition: the area surrounding the nucleus of an atom where electrons are likely to be found
• context: The electron cloud is made up of the atom’s electrons, and it travels in a space around the nucleus.

Question 7

electron dot diagram

Answer 7

• definition: the symbol for the element surrounded by as many dots as there are electrons in its outer energy level
• context: The number of electrons in an element’s outer energy level is shown by the electron dot diagram.

Question 8

element

Answer 8

• definition: a substance made up of only one kind of atom that cannot be divided by ordinary chemical means
• context: Gold is an element that cannot be broken down into any other substance by ordinary chemical means.

Question 9

energy level

Answer 9

• definition: the different positions and specific amount of an electron’s energy
• context: Energy level refers to the different areas of an atom where electrons are found.

Question 10

ion

Answer 10

• definition: an atom that has become electrically charged because it has gained or lost electrons
• context: A negative ion atom has more electrons than a positive ion atom.

Question 11

isotopes

Answer 11

• definition: atoms of the same element that have different numbers of neutrons but the same number of protons
• context: Atoms of all isotopes of carbon contain the same number of protons, but they do not have the same number of neutrons.

Question 12

mass number

Answer 12

• definition: the sum of the number of protons and neutrons in an atom of an element
• context: The number of protons plus the number of neutrons is an element’s mass number.

Question 13

matter

Answer 13

• definition: the term used to describe anything that has mass and takes up space
• context: Matter is made up of atoms.

Question 14

metal

Answer 14

• definition: an element that is malleable, ductile, a good conductor of electricity, and generally has a shiny or metallic luster
• context: Most elements are metals and, therefore, will conduct electricity.

Question 15

metalloid

Answer 15

• definition: an element that has characteristics of both metals and nonmetals and is solid at room temperature
• context: Silicon is a metalloid used to make electronic circuits.

Question 16

molecule

Answer 16

• definition: the smallest part of a compound that still has the properties of the compound
• context: Water is the most abundant molecule on Earth.

Question 17

neutron

Answer 17

• definition: an uncharged particle located in the nucleus of an atom
• context: The nucleus of an atom is made of two kinds of particles: positively charged protons and neutral neutrons.

Question 18

nonmetal

Answer 18

• definition: an element that is usually a gas or a brittle solid and is a poor conductor of electricity and heat
• context: The human body is mostly made up of nonmetals.

Question 19

nucleus

Answer 19

• definition: the positively charged, central part of an atom
• context: The nucleus of an atom is made of two kinds of particles: positively charged protons and neutral neutrons.

Question 20

periodic table

Answer 20

• definition: a chart that organizes the elements by the number of protons in each element’s nucleus
• context: A Periodic Table contains data about the elements.

Question 21

physical property

Answer 21

• definition: a characteristic of matter that can be observed, such as color, shape, smell, taste, texture, mass, volume, and density
• context: A physical property of clay is that it is malleable; squeezing it changes the shape.

Question 22

proton

Answer 22

• definition: a positively charged particle in the nucleus of an atom
• context: Protons are located in the nucleus of an atom.

Question 23

state of matter

Answer 23

• definition: the physical forms in which a substance can exist: solid, liquid, gas, and plasma
• context: Plasma represents the state of matter of the substances in the sun.