Groups of atoms held together by covalent bonds are called:

• elements

• molecules

• mixtures

• alloys

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NGSS.MS-PS1-1

Atoms that gain or lose electrons are called

• alloys

• mixtures

• ions

• elements

Covalent bonding occurs:

• in salts like NaCl.

• when electrons are shared between two atoms.

• only when electrons are shared between two identical atoms.

• when electrons are transferred from one atom to another.

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NGSS.HS-PS1-1

NGSS.HS-PS1-2

Bonding between atoms produces an outermost energy level for each atom filled with:

• 1 electron

• 8 electrons

• 16 electrons

• 32 electrons

Which of the following is the LEAST reactive group?

• Alkali Metals

• Group 2 Metals

• Halogens

• Noble Gases

An atom that acquires an electrical charge by gaining or losing electrons is known as:

• ion

• a free radical

• a hydrate

• a monatomic molecule

Chemical formulas represent the number and element of each type of atom in:

• covalent compounds only

• ionic compounds only

• both ionic and covalent compounds

• mixtures only

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NGSS.MS-PS1-1

In the atom represented below, the small dark circles represent electrons. The number of valence electrons in the atom pictured is:

• 2

• 3

• 5

• 7

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NGSS.MS-PS1-1

The diagram that best represents the Lewis dot diagram of a chlorine atom is:

• 
• 
• 
• 

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NGSS.MS-PS1-1

The Mg atom becomes the ion, Mg2+, when it:

• Gains 2 electrons

• Loses 2 electrons

• Gains 2 protons

• Loses 2 protons