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Criado por Charnanigan14
mais de 10 anos atrás
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Questão | Responda |
Non-metal atoms need to ....(gain/lose) electrons in order to get a stable electronic structure. | Gain |
In covalent bonding, atoms...(take, share) electrons | Share electrons |
A covalent bond is... | When a shared pair of electrons attracts the two atoms forming a bond. |
Covalently bonded substances form... | Molecules |
When drawing covalent bonds, you only draw... | The outer energy level of the atoms |
Carbon forms several bonds which join to give giant covalent structures called... | Macromolecules |
What are the forces called that hold the atoms/ions together? | Electrostatic forces of attraction |
Which direction do these forces of attraction act in? | All directions |
Do ionic compounds have a high or low melting/boiling point? Why? | High Because the intermolecular forces are very strong. A lot of energy is needed to break them |
Do covalently-bonded molecules have a high or low melting/boiling point? Why? | Low Because their intermolecular forces are very weak but the covalent bonds are very strong. Very little energy is needed to overcome them |
Does a simple molecule conduct electricity when a liquid? | No There is NO overall charge in simple molecules. |
Why are larger molecules more likely to be a liquid at room temperature rather than a gas? | Because larger molecules have stronger forces of attraction which are harder to break. They would not be a solid because they do not have as strong bonds as ionic compounds. |
Give an example of an atom which forms a giant covalent structure... | Carbon |
There are no.... in giant covalent structures | Intermolecular forces Every atom is joined by covalent bonds |
Diamond has a three dimensional structure of carbon atoms. Each atom is bonded to ... other atoms. | Four |
Graphite is another form of carbon. Each atom is bonded to ... other atoms. | Three |
Why is graphite so slippery and grey? | Because it is made up of giant, flat two dimensional layers. There are no intermolecular forces between the layers so they can easily slide over each other |
In graphite, each carbon atom has one delocalised electron. What does that mean? | It means that a bonding electron is no longer associated with a particular atom. |
Why does graphite conduct electricity and heat? | Because it has delocalised electrons like the electrons in a metal. |
What are fullerenes? | Fullerenes are molecules that make hexagonal rings of carbon atoms that form cage-like structures when joined together. |
Some fullerenes are... | Nano-sized |
What are some known uses of fullerenes? | Catalysts, lubricants, drug delivery and reinforcing materials. |
What is a catalyst? | A substance that speeds up a chemical reaction. Afterwards, the catalyst is chemically changed. |
Giant Covalent Structures are... | Insoluble in water |
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