ATOMS, ELEMENTS AND COMPOUNDS
What is everything made from?
Atoms
Name one property of a substance
What does a chemical symbol represent?
An element
What is a polymer?
A long chain made from repeating units
Which natural polymer traps air and is a good insulator?
Wool
One type of atom
Which type of element usually conducts electricity very well - metals or non metals?
Metals
What does a chemical formula show?
The types and numbers (or ratio) of atoms in a substance
What is the name of the repeating unit in a polymer?
Monomer
Which property makes rubber useful for tyres?
Flexibility
What is a compound?
Two or more different elements chemically bonded together
What happens when a substance reaches its boiling point?
It changes state from a liquid to a gas
How many hydrogen atoms are in H₂O?
2
Give one example of a natural polymer.
Any one from: Wool, cotton or rubber
What happens to the melting point when polymer chains become longer?
The melting point increases
True or false: A compound has the same properties as the elements that make it up?
False
Complete the sentence: Elements in the same group of the periodic table have similar __________ properties
Chemical
How many atoms are there altogether in NH₃?
4 atoms
Give one example of a synthetic polymer.
Any one from: Plastic (such as poly(ethene), PVC, LDPE or HDPE)
What do plasticisers do to polymers?
They make them more flexible
Why does a compound have different properties from the elements that make it up?
The different atoms are joined together in a new arrangement
Molecules have weaker forces between them than within them. How can this affect melting and boiling points?
It can make substances easier to melt or boil because the forces between molecules are weaker.
What does the small number in a chemical formula tell you?
How many atoms of that element are present
What must happen for a substance to be called a polymer?
A repeating unit (monomer) must repeat many times in a chain.
What effect do cross-links have on a polymer?
They make it harder, stronger and increase its melting point by restricting movement of the chains.