## Why are the masses of some listed as whole numbers in parentheses?

If an element has no stable isotopes, meaning that all known isotopes of that element will undergo nuclear decay, the atomic number is displayed in parentheses.

## What does the mass number symbolize?

The mass number tells us the number (the sum of nucleons) of protons and neutrons 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, atomic number is equal to the number of electrons.

## What does it mean when an element has brackets?

Very often in chemical formulae, we use parentheses to form subgroups of atoms within a molecule. In such a formula, the subscript outside the parentheses means that to count atoms, you must multiply that subscript by the numbers of atoms inside.

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## What is the mass number showing?

The mass number of an atom is its total number of protons and neutrons. Atoms of different elements usually have different mass numbers, but they can be the same. For example, the mass number of argon atoms and calcium atoms can both be 40.

## What is the meaning of a mass number shown in parentheses quizlet?

What is the meaning of a mass number showing parenthesis? The mass number is the sum of the number of protons and neutrons its nucleus.

## What is mass number explain with example?

(ii) Mass number: It is the sum of the number of neutrons and the number of protons. For example, the atomic number of Lithium is 4 which is equal to the number of protons, the number of neutrons of magnesium is 4. The mass number is equal to 8(4+4).

## What is difference between mass number and atomic mass?

Atomic mass is also known as atomic weight. Atomic mass is the weighted average mass of an atom of an element based on the relative natural abundance of that element’s isotopes. The mass number is a count of the total number of protons and neutrons in an atom’s nucleus.

## Why is it called a mass number?

The mass number of an element is named as such because it gives the mass of the total number of protons and neutrons in an element.

## Why is atomic weight in parentheses?

The atomic weight of an element is based on the variety of naturally occurring isotopes of that element and the relative abundance of each. These elements are unstable; that is, their nuclei decompose radioactively. The number in parentheses is the mass number of the most stable or best-known isotope of that element.

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## Do square brackets mean concentration?

Square brackets are often used to represent concentration, e.g., [NaOH] = 0.50 M. Use the capital letter M for molarity, not a lower case m (this is a different concentration unit called molality).

## Why do we put brackets around elements that have charges?

If there’s more than one complex ion in the compound, then brackets are needed. The reason is that you need to put a bracket around the complex ion to show how many of those whole complex ions there are in the compound.

## What is the atomic mass equal to?

The atomic mass of an atom is an empirically measured property, which is equivalent to the sum mass of protons, neutrons, and electrons that make up the atom (with a small adjustment for nuclear binding energy).

## What is the symbol of atomic mass?

The current International System of Units (SI) primary recommendation for the name of this unit is the dalton and symbol ‘Da’. The name ‘unified atomic mass unit’ and symbol ‘ u ‘ are recognized names and symbols for the same unit.

## What is the atomic mass number equal to?

The mass number of an atom is equal to the number of protons plus the number of neutrons that it contains. In other words, the number of neutrons in any atom is its mass number minus its atomic number. Although all atoms of a given element must have the same atomic number, they need not all have the same mass number.