Atomic Number
What does the atomic number of an element represent?
The number of protons in the nucleus of an atom.
What does electronic configuration tell us about an atom?
The arrangement of electrons in different shells of an atom.
What is an ion?
An atom or group of atoms that carries a charge due to loss or gain of electrons.
What is an ionic compound?
A compound formed by the electrostatic attraction between oppositely charged ions.
Between which type of elements is covalent bonding usually formed?
non-metal atoms.
Which subatomic particle determines the atomic number of an element?
Protons
How many electrons can the first shell (K shell) hold at maximum?
2
What is the charge on an atom that loses one electron?
Positive charge.
Which types of ions combine to form an ionic compound?
Positive ions (cations) and negative ions (anions).
How many electrons are shared in a single covalent bond?
2
If an atom has an atomic number of 11, which element is it?
Na
An element has the electronic configuration 2, 8, 1. Identify the element.
Na
What type of ion is formed when an atom gains electrons?
An anion.
Name the ionic compound formed when sodium and sulphur react.
Sodium sulphide
Why can graphite conduct electricity while diamond cannot?
Graphite has free (delocalised) electrons, while diamond does not.
Give atomic number of Ca
20
electronic configuration of an element with atomic number 8.
2,6
Sodium loses one electron during ion formation. What ion does it form? Symbol?
Sodium ion (Na⁺).
Why do ionic compounds usually have high melting points?
strong electrostatic forces of attraction exist between the ions.
Their atoms are connected by a large number of strong covalent bonds in a continuous network. A large amount of energy is required to break these bonds, so they melt only at very high temperatures.
An atom has 17 protons and 18 neutrons. What is its atomic number?
17
Why do atoms form chemical bonds based on their electronic configuration?
To achieve a stable electronic configuration (usually a complete outer shell).
An atom has 11 protons and 10 electrons.
+1
Magnesium forms Mg²⁺ ions and chlorine forms Cl⁻ ions. Write the chemical formula of the ionic compound formed.
MgCl₂.
Why is diamond very hard but graphite is soft, even though both are made of carbon?
In diamond, each carbon atom is strongly bonded to four others in a rigid 3D structure, making it very hard. In graphite, carbon atoms form layers with weak forces between them, so the layers can slide over each other, making it soft.