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Criado por Samina Rashid
mais de 10 anos atrás
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Questão | Responda |
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. |
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