Module 18 Test

What shows the elements a compound contains and the exact number of the atoms of each of those elements in a unit of that compound?

• Elemental analysis
• Molecular weight
• Chemical reaction
• Chemical formula

Tags

NGSS.MS-PS1-1

An electron dot diagram includes the chemical symbol for an element surrounded by dots representing ___________?

• neutrons
• electrons

• valence electrons
• protons

Match the element, with the number of dots to use when making electron dot diagrams.

• 6

• Ba

• 2

• O

• 1

• Ar

• 8

• Li

• 3

• B

Tags

NGSS.HS-PS1-1

How many electrons are needed in the outermost energy level to make it stable?

• 10
• 6
• 8
• 4

True or false: The properties of a compound are often very different from those of its component elements.

• False
• True

Atoms with unstable outer energy levels can lose, gain, or share electrons by combining with ______.

• other atoms
• compounds
• ions
• molecules

When sodium and chlorine combine to form a compound, each sodium atom​ (a)   one electron and each chlorine atom​ (b)   one electron.

• loses
• gains
• Shares

Which concepts is/(are) being illustrated by the diagram?

• In a water molecule the oxygen atom has a complete outer energy level but the hydrogen atoms do not.

• In water, each oxygen atom shares two electrons and each hydrogen atom shares one electron.

• In water, each oxygen atom loses two electrons and each hydrogen atom gains one electron.

• Each hydrogen and oxygen atom has a complete outer energy level.

Tags

NGSS.MS-PS1-1

Which statements about the chemical stability of atoms is true?

• Group 17 elements are stable when their outer energy levels have eight electrons.

• Hydrogen is stable when its outer energy level has two electrons.

• Fluorine is stable when its outer energy level has seven electrons.

• Sulfur is stable when its outer energy level has eight electrons.

• Group 15 elements are stable when their outer energy levels have five electrons.

What is the force that holds atoms together in a compound?

• Chemical bonds
• Gravitational forces
• Magnetic forces
• Nuclear forces

Tags

NGSS.HS-PS2-4