elements and compounds review

How are elements and compounds different?

• An element is a pure substance while a compound is two or more elements combined in a fixed ratio.
• Elements are represented by a chemical formula and compounds are represented by a chemical symbol 
• Elements are NOT pure substance and compounds are pure substances 
• elements are made of two or more substance and compounds are made of one substance 

How many elements are represented in the compound?
Na₂CO₂H₂C

• 5
• 2
• 3
• 4

How do elements and compounds differ?

• elements are not pure substance and compounds are pure substance 
• elements are represented by chemical formulas and compounds are represent by chemical symbols?
• elements are pure substance and compounds are not pure substances 
• elements are can be broken down and compounds can not 

which of the following is a compound?

• Helium
• Hydrogen
• Oxygen 
• Methane

How many elements are represented in the compound?
Na₂CO₂H₂C

• 5
• 2
• 3
• 4

• F
• G
• H
• J

Ca(OH)2→CaO + H2O
In the chemical reaction shown above, the products are best classified as ________________

• three elements 
• two compounds 
• four compounds 
• two elements

CO ± H₂O→CO₂ ± H_{2
Which substance in the equation is considered and element?}

• CO
• H2O
• CO2
• H2

1. Fe
2. Cl₂
3. H20
4.CO2
5. H
6. CaCo
7.C
Which of the following above would be elements?

• Fe, Cl2, H, C
• H2O, Fe, H
• H, C, CO2
• CaCo, Fe

2NO2 + H2O → NO + H2O
How many different elements are present in the formula above?

• 0
• 1
• 2
• 3