Answer:
Two elements in same group having similar properties.
Explanation:
The elements shows similar properties if they have same number of valance electrons.
As we move left to right in periodic table the number of valance electrons increases in case of every element
When we move top to down in the group of periodic table the number of valance electrons remain same. So the elements in same group shows similar properties.
For example:
Fluorine and chlorine are present in same group, both have same valance electrons so they shows similar properties.
Electronic configuration of fluorine.
F₉ = [He] 2s² 2p⁵
Electronic configuration of chlorine.
Cl₁₇ = [Ne] 3s² 3p⁵
Both have same number of valance electrons that's why showing similar physical and chemical properties.
Atomic number is called the number written to the left of a chemical symbol or formula
Answer:
Neon
Explanation:
1s² 2s² 2p⁶ 3s¹ or [Ne] 3s¹
The outer most shell is the 3s¹.
For this atom to achieve stability, if it loses the electron in the 3s shell, it would resemble an inert element with a complete octet configuration. Therefore, the atom would be like:
1s² 2s² 2p⁶ which is the configuration of Ne
Na-24 and Na-23 have the same number of atoms=11, different neutrons(13 and 12),different mass number(24 and 23)
<h3>Further explanation
</h3>
The elements in nature have several types of isotopes
Isotopes have the same number of protons and having a different number of neutrons.
So Isotopes are elements that have the same Atomic Number (Proton)
number of atoms = 11
mass number = 23
number of neutrons=23-11=12
number of atoms = 11
mass number = 24
number of neutrons=24-11=13