7th Grade STAAR Review-SD BOOKLET

What are elements?

• Pure substances represented by a 1 or 2 letter chemical symbol, not able to be broken down chemically, found on the Periodic Table of Elements, with Hydrogen and Helium being the most common elements in the universe.

• Compounds made of two or more elements chemically combined.

• Mixtures of different substances that can be separated physically.

• Substances that can be broken down into simpler substances by chemical means.

Which of the following is an example of an element?

• Water (H2O)

• Gold (Au)

• Glucose (C6H12O6)

• Salt (NaCl)

Match the element with its chemical symbol:

• Sulfur

• S

• Gold

• Sb

• Antimony

• Au

What are compounds?

• Pure substances represented by a chemical formula, composed of two or more different elements chemically combined, able to be broken down chemically, containing different properties than the elements that make them up.

• Mixtures of elements and compounds that can be separated physically.

• Elements that cannot be broken down into simpler substances.

• Substances that are identical to the elements that make them up.

Which of the following is an example of a compound?

• Sulfur (S)

• Antimony (Sb)

• Glucose (C6H12O6)

• Gold (Au)

Match the compound with its chemical formula:

• NaCl

• C6H12O6

• C6H12O6

• NaCl

• H2O

• H2O

What does a subscript in a chemical formula represent?

• The type of element in a molecule

• The number of atoms of an element in a molecule

• The charge of an ion

• The state of matter of a substance

What does a coefficient in a chemical formula represent?

• The type of molecule

• The number of molecules

• The mass of the molecule

• The charge of the molecule

In the chemical formula C6H12O6, how many atoms of Carbon are present?

• 6

• 12

• 18

• 24

In the chemical formula 2Fe2O3, how many total atoms are present?

• 10

• 8

• 12

• 14