<u>Answer: </u>The correct statement is X is the effective nuclear charge, and it increases across a period.
<u>Explanation:</u>
We are given that:
X = number of protons − number of core electrons
Effective nuclear charge is defined as the actual nuclear charge (Z = number of protons) minus the screening effect caused by the electrons present between nucleus and valence electrons. These electrons are the core electrons.
The formula used for the calculation of effective nuclear charge given by Slater is:
where,
= effective nuclear charge
Z = atomic number or actual nuclear charge or number of protons
= Screening constant
The effective nuclear charge increases as we go from left to right in a period because nuclear charge increases with no effective increase in screening constant.
Hence, the correct answer is X is the effective nuclear charge, and it increases across a period.
Answer:-
Electrons or Protons
Explanation:-
Atomic number (Z) is defined as:
>>“The total number of protons in the nucleus of an atom is called atomic number”. All atoms of an element have the same number of protons and electrons.
>>“The total number of protons in the nucleus or electrons revolving around the nucleus of an atom”.
Example:
For instance, Hydrogen has the Atomic number(Z) 1.
Helium has the atomic number 2.
Oxygen has the atomic number 8.
| Note | Atomic number is represented by “Z”. And some ppl don’t consider the 2nd definition it’s upto u to do both or the standard one.
The changes that are common between sauce burning on a stove, and jewelry tarnishing, which is a chemical change.
How to define chemical and physical changes?
Chemical Change-
Any alteration that produces new chemical substances with distinct properties is considered a chemical change. Chemical reactions involve the rearrangement and recombination of elements and compounds to create new substances. Examples of chemical changes are listed below:
- Burning
- Digestion
- chemicals changing colors
- Tarnishing
- compost rotting
Physical Change-
A substance is not destroyed or transformed into something new by physical changes. A substance can undergo physical changes that alter its shape, size, or phase. The constituents of an element or compound do not change during a physical change. Examples of physical changes are listed below:
- Boiling water
- Chopping, Cutting, Carving
- Evaporation
- Freezing, Melting, Condensation
To know more about chemical and physical changes, visit the given link:
brainly.com/question/20628019
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