It is essential that all chemistry students must know this topic very well, in order to handle the rest of chemistry topics. Let’s look at some key points:
Atoms consists of 3 types of particles:
- Protons (+ve charge)
- Neutrons (Neutral)
- Electrons (-ve charge)
Protons and Neutrons are located inside the Nucleus of the atom while Electrons are arranged in Shells surrounding the nucleus. Each shell can hold a maximum number of electrons as shown below:
- Shell 1: 2
- Shell 2: 8
- Shell 3: 8
The electrons that are furthest away from the Nucleus is called the Outermost Shell Electrons or Valence Electrons. These electrons is very important because they are used to form Chemical Bonds.
- Metals tend to fewer outer shell electrons – 1, 2 or 3 electrons
- Non-metals tends to have many outer shell electrons
Number of Protons in an atom is called the PROTON NUMBER.
Number of Protons + Neutrons in an atom is called the NUCLEON NUMBER.
The number of Protons?= number of Electrons, and bcos of this, the +ve and -ve charges balance each other are all atoms are Neutral.
Isotopes is another important term you would need to know for GCE O Level Chemistry (also IGCSE, IB and IP Chemistry).
Isotopes are atoms of the Same Element with same number of Protons (and thus Electrons) but different number of Neutrons.
Isotopes have slightly different physical properties but have identical chemical properties because they have the same number and arrangement of Electrons.
Now, let’s try out some O Level Chemistry – type questions:
Question 1: Based on topic “Atomic Structure”
Which element has an isotope that does not contain neutrons?
Question 2: Based on topic “Atomic Structure”
An atom of Ne-20 loses two protons and two neutrons from its nucleus and forms the atom X.
a) What would be the number of protons and neutrons in the atom of X formed? (2 mark)
b) What is the symbol for X, including the proton and nucleon number? (1 mark)
Question 3: Based on topic “Atomic Structure”
What do the electronic configurations of the alkali metals (Group I elements on the Periodic Table) have in common? (1 mark)
Attempt the above questions and leave your answers and reasonings in the “Leave A Reply” section below.
Look forward to your participation. =)
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Stay tuned for the next post!