What are the only parts of an atom that make chemical bonds?
valence electrons
100
T/F: A change in state is a sign of a chemical reaction
False
100
Which of the following are used to balance an equation?
a. subscripts c. reactants
b. coefficients d. products
coefficients
200
What do atoms gain, lose, or share when they bond?
electrons
200
What are the charged particles that form when atoms gain or lose electrons?
ions
200
What happens in an exothermic reaction?
Energy is released
200
Nitrogen dioxide is a covalent compound. How many oxygen atoms are in a nitrogen dioxide molecule?
2
300
What term is used for the joining of atoms to form new substances?
chemical bonding
300
T/F: Covalently bonding compounds have a low melting and boiling point
True
300
A precipitate is usually a(an)
solid
300
A calcium carbonate molecule has 1 calcium (Ca) atom, 2 oxygen (O) atoms, and 1 carbon (C) atom. Which of the following shows the chemical formula for calcium carbonate?
CaCO2
(2 is a subscript)
400
What is a bond that forms when valence electrons are transferred from one atom to another?
ionic bond
400
How many valance electrons does oxygen have?
6
400
How do substances form during a chemical reaction?
Chemical bonds break; atoms rearrange; new chemical bonds form.
400
State the law of conservation of mass
Mass cannot be created or destroyed in a chemical reaction.
500
Why don’t noble gases normally form chemical bonds?
They have full outer energy levels
500
How many electrons would it take to fill the outermost energy level of most atoms?
8
500
What comes before the yield arrow in a chemical formula
reactants
500
If a chemical symbol in a chemical formula has no subscript, it means