Busy. Please wait.

show password
Forgot Password?

Don't have an account?  Sign up 

Username is available taken
show password


Make sure to remember your password. If you forget it there is no way for StudyStack to send you a reset link. You would need to create a new account.
We do not share your email address with others. It is only used to allow you to reset your password. For details read our Privacy Policy and Terms of Service.

Already a StudyStack user? Log In

Reset Password
Enter the associated with your account, and we'll email you a link to reset your password.
Didn't know it?
click below
Knew it?
click below
Don't know
Remaining cards (0)
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.

  Normal Size     Small Size show me how

Science C2 Topic 3

Edexcel GCSE additional science chemistry: covalent compounds and separation

What is a covalent bond? A pair of electrons that are shared by two atoms that are either the same or different non-metals
How many electrons can there be in a covalent bond? Only 2
Show the covalent bonding for methane CH4
Show the covalent bonding for oxygen O2
What are simple molecular covalent substances and what are some properties of them? Covalent molecules with a discrete formula. Properties: comparatively low melting and boiling points as there are weak bonds, poor electrical conductors
What are giant molecular covalent substances and what are some properties of them? Covalent substances where there are billions of atoms joined by covalent bonds. Properties: high boiling and melting points due to strong covalent bonds, some conduct electricity (graphite) but most don't
What are some properties and uses of diamond? Diamond is a carbon allotrope, a giant molecular covalent substance (each carbon atom is joined to 4 atoms in a tetrahedral pattern) High boiling/melting points. Very hard- cutting tools. Sparkle and reflects light- jewellery. Doesn't conduct electricity
What are some properties and uses of graphite? Carbon allotrope- giant molecular covalent substance (each C atom is joined to 3 atoms in a layer and delocalised electrons bond layers together) High melting/boiling points. Electrical conductor- electrodes. Rubs away in layers- pencil lead & lubricant
What does it mean if liquids are immiscible? They do not mix when put together, instead they form two layers e.g. oil and water
How do you separate immiscible liquids? Separating funnel- liquids are put in the funnel and are left to separate out, then the tap is opened and the bottom liquid runs out. When the bottom liquid has all run out, the tap is closed.
What does it mean if liquids are miscible? They mix when put together and form one layer e.g. alcohol and water
How do you separate miscible liquids? Fractional distillation- heat the liquids and allow them to evaporate, then put them in a fractionating column and wait for them to condense at different points. Highest boiling point condenses at the bottom. Lowest boiling point condenses at the top
How do you separate the components of liquid air? Air is cooled so water can freeze and be removed. Air is cooled to -200 degrees c and is liquefied, then is wamred to -185 degrees c in a fractionating column. Liquid nitrogen rises to the top and is collected. Liquid oxygen is collected at the bottom.
What is paper chromatography used for? It is used to separate out different solutes dissolved in one solvent e.g. in inks
How does paper chromatography work? The samples are put on a pencil line on chromatography paper and are placed in a beaker with water at the bottom. The water soaks up the paper and carries the solutes with it producing a chromatogram with separated solutes
Why do solutes spread out in chromatography? They all have different solubilities so move at different speeds
What is the Rf value, how is it calculated and why is it used? It is a way of identifying the solutes dissolved in a solvent- Rf value = distance moved by compounds / distance moved by solvent. It is used in forensics and in the food industry to identify specific compounds
Created by: 11043



Use these flashcards to help memorize information. Look at the large card and try to recall what is on the other side. Then click the card to flip it. If you knew the answer, click the green Know box. Otherwise, click the red Don't know box.

When you've placed seven or more cards in the Don't know box, click "retry" to try those cards again.

If you've accidentally put the card in the wrong box, just click on the card to take it out of the box.

You can also use your keyboard to move the cards as follows:

If you are logged in to your account, this website will remember which cards you know and don't know so that they are in the same box the next time you log in.

When you need a break, try one of the other activities listed below the flashcards like Matching, Snowman, or Hungry Bug. Although it may feel like you're playing a game, your brain is still making more connections with the information to help you out.

To see how well you know the information, try the Quiz or Test activity.

Pass complete!

"Know" box contains:
Time elapsed:
restart all cards