Alchemy Quiz 13

Why do different atoms bond together to make compounds?

• Because atoms need an equal number of protons and electrons.

• So the atoms can get rid of extra energy in their electrons.

• Because the atoms are more stable with full outer shells of electrons.

• So the atoms can gain electrons.

Answer explanation

Why are noble gases unreactive? How can other elements be like noble gases?

Which statement best illustrates the “rule” for forming ionic compounds?

• The total number of electrons and protons must be a multiple of 8.

• The total number of electrons must be a multiple of 8.

• The total number of ions must be a multiple of 8.

• The total number of valence electrons must be a multiple of 8.

Answer explanation

You may wish to review your data for Alchemy Lessons 20 and 21.

Bromine gains one electron to form which ion?

• Br⁺¹

• Br^-1

• Br⁺²

• Br^-2

Answer explanation

If an atom loses an electron, it will have more protons than electrons for a net positive charge.

If an atom gains an electron, it will have more electrons than protons for a net negative charge.

Mg and O combine to form the ionic compound magnesium oxide. What is the correct formula for magnesium oxide?

• MgO₂

• Mg₂O

• MgO

• Mg₂O₂

Answer explanation

Group 2A and Group 6A elements combine in a one-to-one ratio.

Tags

NGSS.MS-PS1-1

What is the correct formula for the compound magnesium chloride?

• MgCl₂

• Mg₂Cl₃

• Mg₂Cl

• MgCl

Answer explanation

Group 2A and Group 7A elements combine in a one-to-two ratio.

Tags

NGSS.MS-PS1-1

Which of these compounds will NOT form?

• ArCl₂

• Na₂S

• AlCl₃

• NaCl

Tags

NGSS.HS-PS1-1

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Which of these compounds does NOT occur?

• LiCl

• MgCl₂

• AlCl₃

• CaCl

Answer explanation

Group 2A and Group 7A elements combine in a one-to-two ratio.

Tags

NGSS.MS-PS1-1

Which compound can be made with these cards?

• K₂O

• K₂Ca

• K₂Cl₂

• Cl₂O

• KO

Answer explanation

In an ionic compound, the metal is always listed first. Group 1A combines with Group 6A in a two-to-one ratio.

Tags

NGSS.MS-PS1-1

An ionic compound is formed when:

• a neutral compound gains an electron.

• a cation bonds to an anion.

• a hydroxide ion bonds to a nitrate ion.

• an atom gains an electron.

Answer explanation

Cations are positively charged metals, anions are negatively charged nonmetals.

Tags

NGSS.MS-PS1-5

Two groups of the periodic table are highlighted in the image. What is the metal to nonmetal ratio of ionic compounds formed from these groups?

• 1:1

• 1:2

• 2:1

• 2:7

Answer explanation

Group 2A wants to give up two electrons. Group 7A can only gain one each, so how many from 7A do you need to combine with one from Group 2A?

Tags

NGSS.MS-PS1-1

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