OCR - C5.1 | Flashcards

Question	Answer
Name three gases found in the air, which are also elements.	oxygen, nitrogen and argon
Name 2 gases found in the air which are compounds	Methane and carbon dioxide
What % of the air is 1. nitrogen 2. oxygen 3. carbon dioxide 4. argon	1. 78% 2. 21% 3. 0.04% 4. 1%
Use a periodic table: Name 1. 2 compounds made of a metal and non-metal 2. 2 compounds made of non-metals	1. sodium chloride, magnesium oxide, aluminium flouride 2. water, carbon dioxide, methane, hydrogen sulphide
What is a molecule?	A n element or compound made of 2 or more non-metal atoms covalently bonded together
Why do gases have low melting and boiling points?	Because they are made up of small molecules held together by weak forces of attraction.
Why don't molecular compounds conduct electricity?	Molecules don't have a charge, so they can't carry a current
What type of bonds do molecules have?	Covalent
True or false: oxygen is a gas at room temperature because the forces between atoms are weak.	False, oxygen is not atoms it is molecules.
True or false: methane CH4, has a lower boiling point than ethane C2H6, because there are less bonds to break	False! Yes there are less bonds to break in methane but if you broke the bonds holding C and H together, then we wouldn't have methane anymore. When you boil a molecular compound we are breaking the forces of attraction BETWEEN molecules not within molecules. Methane has a lower boiling point because it is smaller and has weaker forces of attraction between molecules.

OCR - C5.1

	Created by Samina Rashid about 10 years ago