5. (a) Define atomic number.
(b) Consider the elements of the second and third periods of the periodic table of the elements (Li to Ne and Na to Ar). See page 79 o... show full transcript
Worked Solution & Example Answer:5. (a) Define atomic number - Leaving Cert Chemistry - Question 5 - 2014
Step 1
Define atomic number.
96%
114 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
The atomic number is defined as the number of protons in the nucleus of an atom.
Step 2
In terms of the distribution of electrons, what common feature is found in
99%
104 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
i) Atoms of elements in the same group, such as lithium and sodium, have the same number of electrons in their outer (valence) shell.
ii) Atoms of elements in the same period, such as carbon and nitrogen, have the same number of occupied shells.
Step 3
Why do the elements of group 18 (noble gases) have very low chemical reactivity?
96%
101 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
The elements of group 18 have a stable electron arrangement with a full outer shell of electrons. This stability means that noble gases do not readily gain, lose, or share electrons, resulting in very low chemical reactivity.
Step 4
What is the arrangement of electrons in the main energy levels (shells) in
98%
120 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
i) An atom of magnesium (Mg) has an electron arrangement of 2, 8, 2.
ii) An atom of oxygen (O) has an electron arrangement of 2, 6.
Step 5
Write the name and formula of the compound formed between magnesium (Mg) and oxygen (O).
97%
117 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
The compound formed between magnesium and oxygen is called magnesium oxide, and its formula is MgO.
Step 6
Give one characteristic of compounds with this type of bond.
97%
121 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
Compounds with ionic bonds, such as magnesium oxide, typically have high melting points and can conduct electricity when dissolved in water or molten.
Join the Leaving Cert students using SimpleStudy...
