Atoms and Elements

How many known elements exist?

• about 100
• fewer than 50
• exactly 74
• 1,000

The smallest particle of matter is called _______.

• a molecule
• an atom
• a shell
• a mixture

Mass is _________.

• the length of an atom's nucleus
• the center of a compound
• another name for mixtures that go together
• the amount of matter in an object

Because of gravity

• we can jump higher on a trampoline
• we need to eat more vegetables
• objects have weight
• apples have seeds

Gold is an element because ___________________.

• it is made up of only gold atoms
• it is expensive
• it is a metal
• it is heavier than other metals

When two or more atoms link together they are called ________.

• a shell
• an electron
• a molecule
• a cluster

^{Look at the graphic used to illustrate the technology of High-Tech Ink. What separates the light and dark states in each example?}

• gray ink
• air
• milky fluid
• clear fluid

This diagram illustrates how chemical elements share electrons to form a molecule of water?

• hydrogen and oxygen
• oxygen and oxygen
• hydrogen and electrons
• hydrogen and water