The Atomic Number Tells You The Number Of

by



  1. What Does The Atomic Number Tell You
  2. The Atomic Number Tells You The Number Of Blank In One Atom Of An Element
What does the atomic number tell youThe Atomic Number Tells You The Number Of

The atomic number tells you the number of protons in an atom. The atomic number is right above the element symbol. Example: 36 83.80 In this example, 36 is the atomic number, so the number of. The atomic number or proton number (symbol Z) of a chemical element is the number of protons found in the nucleus of every atom of that element. The atomic number uniquely identifies a chemical element. It is identical to the charge number of the nucleus. In an uncharged atom, the atomic number is also equal to the number of electrons.

Learning Objective

  • Determine the relationship between the mass number of an atom, its atomic number, its atomic mass, and its number of subatomic particles

Key Points

  • Neutral atoms of each element contain an equal number of protons and electrons.
  • The number of protons determines an element’s atomic number and is used to distinguish one element from another.
  • The number of neutrons is variable, resulting in isotopes, which are different forms of the same atom that vary only in the number of neutrons they possess.
  • Together, the number of protons and the number of neutrons determine an element’s mass number.
  • Since an element’s isotopes have slightly different mass numbers, the atomic mass is calculated by obtaining the mean of the mass numbers for its isotopes.

Terms

  • atomic massThe average mass of an atom, taking into account all its naturally occurring isotopes.
  • mass numberThe sum of the number of protons and the number of neutrons in an atom.
  • atomic numberThe number of protons in an atom.

Atomic Number

Neutral atoms of an element contain an equal number of protons and electrons. The number of protons determines an element’s atomic number (Z) and distinguishes one element from another. For example, carbon’s atomic number (Z) is 6 because it has 6 protons. The number of neutrons can vary to produce isotopes, which are atoms of the same element that have different numbers of neutrons. The number of electrons can also be different in atoms of the same element, thus producing ions (charged atoms). For instance, iron, Fe, can exist in its neutral state, or in the +2 and +3 ionic states.

Mass Number

An element’s mass number (A) is the sum of the number of protons and the number of neutrons. The small contribution of mass from electrons is disregarded in calculating the mass number. This approximation of mass can be used to easily calculate how many neutrons an element has by simply subtracting the number of protons from the mass number. Protons and neutrons both weigh about one atomic mass unit or amu. Isotopes of the same element will have the same atomic number but different mass numbers.

Scientists determine the atomic mass by calculating the mean of the mass numbers for its naturally-occurring isotopes. Often, the resulting number contains a decimal. For example, the atomic mass of chlorine (Cl) is 35.45 amu because chlorine is composed of several isotopes, some (the majority) with an atomic mass of 35 amu (17 protons and 18 neutrons) and some with an atomic mass of 37 amu (17 protons and 20 neutrons).

Given an atomic number (Z) and mass number (A), you can find the number of protons, neutrons, and electrons in a neutral atom. For example, a lithium atom (Z=3, A=7 amu) contains three protons (found from Z), three electrons (as the number of protons is equal to the number of electrons in an atom), and four neutrons (7 – 3 = 4).

Show SourcesTells

Boundless vets and curates high-quality, openly licensed content from around the Internet. This particular resource used the following sources:

http://www.boundless.com/
Boundless Learning
CC BY-SA 3.0.

http://en.wiktionary.org/wiki/atomic_number
Wiktionary
CC BY-SA 3.0.

http://www.boundless.com//biology/definition/atomic-mass–2
Boundless Learning
CC BY-SA 3.0.

“A-level Chemistry/OCR/Atoms, Bonds and Groups/Atoms and Reactions/Atoms.”

http://en.wikibooks.org/wiki/A-level_Chemistry/OCR/Atoms,_Bonds_and_Groups/Atoms_and_Reactions/Atoms
Wikibooks
CC BY-SA 3.0.

http://cnx.org/content/m44390/latest/?collection=col11448/latest
OpenStax CNX
CC BY 3.0.

What does the atomic number of an element tell you?

1 Answer

Identifies the number of protons a single atom of the element contains.

Explanation:

The atomic number helps people identify elements according to the number of protons one atom of the element has. It essentially defines the element.

While having a neutral charge, it also provides the number of electrons the element has (in one atom).

While isotopes are a thing, it doesn't completely change the atom.

What Does The Atomic Number Tell You

Have a different number of neutrons, you have an isotope, but if the number of protons differ, you are dealing with an entirely different element (in neutral state - reactions are out of the picture).

Hope this helps :)

The Atomic Number Tells You The Number Of Blank In One Atom Of An Element

Related questions