Counting Atoms

What is a valence electron?

• An electron in the outer most occupied energy level of an atom
• An electron that has properties similar to a transition metal
  
• Electrons with high reactivity
• Noble gases

A pure substance that cannot be broken down into simpler substances.

• element
• compound
• molecule
• carbon dioxide

How many Valence Electrons does Argon have?

• 2
• 3
• 8
• 18

The law of conservation of matter states that

• chemical reactions change matter.
• in chemical reactions, the identity of reactants and products is conserved.
• atoms are neither created nor destroyed in chemical reactions.
• a chemical equation must be balanced.

Tags

NGSS.MS-PS1-5

2H₂ + O₂ --------> 2H₂O What  are the reactants?

• ----->
• 2H₂O
• 2H₂ +O₂

Tags

NGSS.MS-PS1-1

NGSS.MS-PS1-2

2H₂ + O₂ ----> 2H₂O What is the product?

• ------>
• 2H₂O
• 2H₂+ O₂

Tags

NGSS.MS-PS1-5

NGSS.MS-PS1-2

What is a coefficient?

• The small number on the right of the chemical symbol.
• The large number to the left of a formula.

Tags

NGSS.MS-PS1-5

A subscript is the small number below a(n) ________ that tells the number of _______ of that element.

• element symbol; atoms
• atom; element symbol
• subscript; protons
• compound; elements

Tags

NGSS.MS-PS1-1

The blue numbers in the image below represent ________

• I don't know, and don't want to try
• coefficients
• subscripts
• none of the answers are correct

Tags

NGSS.MS-PS1-5

The red numbers in the image below represent ________

• subscripts
• coefficients
• I don't know, and don't want to try
• None of the answers are correct

Tags

NGSS.MS-PS1-1