Lustig-Science 9th Week Review

​The H₂O compound (water) has atoms that are chemically bonded, therefore, water is a chemical compound.

Multiple Select

Which of these are representations of compound molecules that may be found in an air sample? Select all three.

​Elements are arranged in order of number of protons, regardless of its atomic mass.

​A neutral atom has the same number of

protons and electrons (equal (+) & (-) charges.​

​Law of conservation of mass states that mass is created in a physical change. It stays the same.

​Al₂(SO₄)₃

​The above compound has 2 Aluminum atoms, 3 Sulfur Atoms, and 12 Oxygen atoms. The total number of atoms is 17.

​Al x 2- aluminum has a subscript of 2, so there are two atoms

S x 3 - Sulfate has no subscript, so multiply 1 by the subscript after the parenthesis, which is 1x3. There are 3 atoms of Sulfur

O x (4x3)​ - Oxygen has a subscript of 4, so there are 4 atoms inside the parenthesis, then multiply by the subscript outside the parenthesis. There are 4x3 = 12 atoms of oxygen

Fill in the Blanks

____Al + ____Br₂ --> ____AlBr₃

To balance the above equation, you need to add coefficients on each side of the equation. Enter your answer in this format (1,2,3) no spaces between numbers. Separate with a comma.