Answer:
Na-O
Be-S
Explanation:
ionic bonds= metal and non metal
Answer: The number 4 indicates 4 electrons.
Explanation: We are given an electronic configuration, which is:

Here,
- The letters denote the sub-shells of an element.
- The numbers written before the letters which are 1, 2 and 2 represents the Principle Quantum Number and these represents the energy level of the sub-shells.
- The number which are written in the superscripts which are 2, 2 and 4 denotes the electrons which are present in the sub-shell.
Hence, 4 indicates 4 electrons present in 2p sub-shell.
Answer:
They are listed below
Explanation:
The 5 things that the periodic table includes are;
1. Name of the element
2. The symbol of the element
3. Atomic number of the element
4. Relative atomic mass
5. Electron configuration