Chemistry 2a Summary Questions Flashcards
What do mass number and atomic number represent?
mass number = number of protons + neutrons
atomic number = number of protons
What are the relative masses of the three particles in an atom?
Proton = +1 Neutron = +1 Electron = 0.0005
What is a compound?
Two or more substances that are chemically bonded together that are hard to separate once bonded.
Define the term isotope.
An atom of an element with the same number of protons but different number of neutrons.
Describe the process of ionic bonding.
Atoms with a small number of electrons on their outer shell give the electrons to one with an almost full outer shell. This makes them be positive ions and negative ions. Therefore, they are attracted as opposite forces attract.
What are the main properties of ionic compounds?
1) high melting and boiling points
2) dissolve easily in water
What type of ion do elements from the following groups form?
a) Group 1
b) Group 7
a) positive ions
b) negative ions
What is covalent bonding?
Where atoms share electrons, between two non-metals.
What are the two types of covalent substances? Give 3 example for each.
1) simple covalent bonds - water, oxygen and chlorine
2) giant covalent structures - granite, diamond and silica
List three properties of metals and explain how metallic bonding causes these properties.
1) malleable - layers that slide over each other
2) conduct electricity and heat well - sea of delocalised electrons
3) high melting and boiling points - strong electrostatic forces of attraction
Why are alloys harder than pure metals?
They are made up of different sized atoms so the layers are disrupted, meaning they can’t slide over each other well.
What is the difference between thermosetting and thermosoftening polymers and why?
Thermosetting polymers have cross-links between the polymer chains so when they are heated and moulded they cannot be changed shape. Thermosoftening polymers don’t have the links so overtime they are heated they are able to be remoulded.
