Define the term ‘energy levels’.
Energy levels or shells are imaginary lines circling the nucleus, these lines are what electros travel on.
Identify the number of electrons each shell normally holds.
The number of electrons on each shell varies on the shell level. The number of electrons on each shell gets progressively bigger, the sequence from the inner shell to the outer is 2; 8; 18(or 8); 32(or 8).
Clarify what the electronic configuration of an atom shows.
Depending on how many electrons the atom has, the electronic configuration is different. If an atom has 10 electrons like neon, 2 fit into the first shell, 8 in the next. This would be written as 2,8.
Describe the electronic configuration of magnesium.
Magnesium has 12 electrons, so 2 are able to go into the first shell, 8 in the next, and then 2. Making an electronic configuration of 2,8,2
Periods, groups and electrons:
Describe what the following have in common:
Atoms in the same group
They have the same number of electrons on the outer shell (helium is an exception with 2 rather than 8)
Atoms in the same period
Atoms in the same period have the same number of shells
Atoms that react and atoms that don’t:
Identify which group contains elements that rarely react.
The group that contains the noble gasses is the group VIII
Distinguish between atoms that react and atoms that don’t react.
All the atoms that are nobel have the outer shell ending with 8 electrons. The Noble gases are helium, neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and radon (Rn), these gases do not react but all the others do.
Compare a chlorine atom with a chloride ion.
A chlorine atom has an electronic configuration of 2,8,7 so when it becomes an ion, it gains one electron changing it’s electronic configuration to 2,8,8 making it negative.
Describe what happens when a sodium ion forms.
A sodium atom has an electronic configuration of 2,8,1 so when it becomes an ion, it loses one electron changing it’s electronic configuration to 2,8 making it positive.
Explain the difference between the formation of a positive ion and a negative ion. Use a diagram to clarify your answer.
When an atom turned into an ion and becomes positive, it loses an electron to another source and when the atom turned into an ion and becomes negative, it gains an electron.
Identify three positive and three negative ions by name and symbol.
Explain why noble gases do not form ions.
Noble gases do not form ions because they do not react with any other element
Sodium chloride has charges but no overall charge. Explain.
Sodium chloride has no overall charge because its two ions are either losing or gaining an electron, making it equal.
Identify the period and group these atoms belong to:
an atom with configuration 2,4
Period 2, IV
an atom with configuration 2,8,6
Period 3, VI
an atom with seven electrons
Period 2, V
an atom with 15 electrons
Period 3, V
Period 4, II
Period 2, VIII
Write the electronic configuration of these atoms.
an atom in Period 2, Group VI
an atom in Period 3, Group VIII
an atom in Period 1, Group VIII (be careful)
an atom of Mg
an atom of S