what is the difference between atomic weight & atomic number?

Question

explain atomic weight & atomic number

Answer 1

Atomic Weight = No. of Protons + No. of Neutrons
Atomic Number = No. of Protons

Answer 2

Atomic Number Vs Atomic Weight

Answer 3

Atomic Number And Atomic Weight

Answer 4

All okay but not thorough explanations.

Yes, the atomic number is the number of protons in the nucleus and this determines the element. This positive charge determines the number of electrons which, when combined with shell filling rules, determines the chemistry of that element.

Neutrons add mass to the nucleus without adding charge which makes an 'isotope' {same number of protons so same element with different weight} which has the same chemistry because it has the same electron structure.

Now, the atomic mass is *almost* the sum of the mass of those protons and neutrons but not quite.

Believe it or not, Einstein now comes into the picture; when you try hold like-charged particles together, you have to use energy (called the binding energy) to do that and relativity says that energy can be converted into mass and vice versa.

Therefore, the atomic mass is the sum of the masses of the protons and neutrons *minus* the binding energy.

Finally, we are in position to discuss atomic weight which [per vishnu's *direct quote* from Wiki - ref 3 below] is the weighted average of the atomic masses of those isotopes that exist in nature [ref 4] and is determined by be weighing.

Many people use the terms interchangeably but that really isn't correct.

Note - the first reference is a good source of science information and shows an example for helium where the total parts should add up to 4.03188 (atomic mass) units but instead adds up to only 4.00153 units [see the reference for an explanation of just how large this is].

Answer 5

Definition: The average mass of the atoms of an element. This is a weighted average of the naturally-occurring isotopes.
Also Known As: Atomic Mass.

The atomic number is equal to the number of protons in an atom's nucleus. The atomic number determines which element an atom is.

Answer 6

Atomic Weight :
The atomic mass (ma) is the mass of an atom at rest, most often expressed in unified atomic mass units.] The atomic mass is sometimes incorrectly used as a synonym of relative atomic mass, average atomic mass and atomic weight; however, these differ subtly from the atomic mass. The atomic mass is defined as the mass of an atom, which can only be one isotope at a time and is not an abundance-weighted average. The actual numerical difference is usually very small such that it does not affect most bulk calculations but such an error can be critical when considering individual atoms.

Atomic Number :
The atomic number (also known as the proton number) is the number of protons found in the nucleus of an atom. It is traditionally represented by the symbol Z. The atomic number uniquely identifies a chemical element. In an atom of neutral charge, the number of electrons also equals the atomic number.

The atomic number is closely related to the mass number, which is the number of protons and neutrons in the nucleus of an atom. The mass number defines the isotope of the element and often comes after the name of the element, e.g. carbon-14 (used in carbon dating)

Each element has a specific set of chemical properties as a consequence of the number of protons in its nucleus. The charge of an atom's nucleus defines its electron configuration based on principles of quantum mechanics. The form of each element's electron shells, particularly the valence shell, is the primary factor in determining its chemical bonding behavior.

Answer 7

This Site Might Help You.

RE:
What is the difference between atomic weight & atomic number?
explain atomic weight & atomic number

Answer 8

Atomic weight is the weight of an atom devided by the weight of an hydrogen atom. Atomic number is the number of protons present in the atom. These are applied for ions also.

Answer 9

atomic weight is defined as the mass of the atom with respect to 1/12 the mass of carbon 12 atom

The atomic mass (ma) is the mass of an atom at rest, most often expressed in unified atomic mass units.[1] The atomic mass is sometimes incorrectly used as a synonym of relative atomic mass, average atomic mass and atomic weight; however, these differ subtly from the atomic mass. The atomic mass is defined as the mass of an atom, which can only be one isotope at a time and is not an abundance-weighted average. The actual numerical difference is usually very small such that it does not affect most bulk calculations but such an error can be critical when considering individual atoms. The relative atomic mass (Ar) (also known as atomic weight and average atomic mass) is the average of the atomic masses of all the chemical element's isotopes as found in a particular environment, weighted by isotopic abundance. atomic number is the number of protons or electrons in the of an atom.

Answer 10

The atomic number is the number of protons in an atom's nucleus. The atomic mass or weight is the combination of protons and neutrons. Electrons are so tiny that they hardly affect the mass of an atom at all.

EX. A helium atom has two protons and two neutrons in its nucleus. The atomic number of helium is 2 because it has two protons. But an atom is more than just the sum of its protons (lol), so the atomic mass of helium is 4.