explain the periodic property of valence and atomic radius
Answers
Answer:
Generally, the atomic radius decreases across a period from left to right and increases down a given group. ... Moving down a group in the periodic table, the number of electrons and filled electron shells increases, but the number of valence electrons remains the same.
Answer:
Explanation:
the periodic property of valence and atomic radius
valence
The combining capacity of an atom is known as its valency. It is equal to the number of electrons that an atom can accept or donate in order to complete its octet. As we move down a group, the number of electrons in the valence shell remains the same. Hence the valency of a group is constant. Valency depends on the number of electrons in the outermost shell of an atom. If the number of electrons is 1, 2, 3, 4 then the respective valences will be 1, 2, 3, 4. If the number of electrons in the outermost shell will be 5, 6, 7 then the valency will be 8 – 5 = 3, 8 – 6 = 2 and 8 – 7 = 1. Valency is the combining capacity of an atom hence will always have a positive value and largely affects the periodic properties.
Atomic Radius
We can never determine the atomic radius of an atom because there is never a zero probability of finding an electron, and thus never a distinct boundary to the atom. All that we can measure is the distance between two nuclei (internuclear distance). A covalent radius is one-half the distance between the nuclei of two identical atoms. An ionic radius is one-half the distance between the nuclei of two ions in an ionic bond. The distance must be apportioned for the smaller cation and larger anion. A metallic radius is one-half the distance between the nuclei of two adjacent atoms in a crystalline structure. The noble gases are left out of the trends in atomic radii because there is great debate over the experimental values of their atomic radii. The SI units for measuring atomic radii are the nanometer (nm) and the picometer (pm). 1 nm = 1 X 10-9 m; 1 pm = 1 X 10-12 m.