# Atomic Number 17

### How many valence electrons are in an atom of chlorine?

Shreyans Bhansali · Ernest Z. · Ramith Hettiarachchi · Christopher P. · dwayne

Chlorine (Cl) - Atomic Number 17. Chlorine (Cl) exists as a yellow green gas with a pungent smell. It has the atomic number 17 in the periodic table and belongs in Group 17, the Halogens. It is a non metal with the symbol Cl. Chlorine much like other Halogens has antiseptic properties. It is used in swimming pools commonly and also making.

#### Explanation:

The electron configuration of chlorine is $1 {s}^{2} 2 {s}^{2} 2 {p}^{6} 3 {s}^{2} 3 {p}^{5}$ or $' \left[N e\right] ' 3 {s}^{2} 3 {p}^{5}$.

• Atomic Number: 17: Atomic Mass: 35.453 atomic mass units: Number of Protons: 17: Number of Neutrons: 18: Number of Electrons: 17: Melting Point-100.98° C: Boiling Point-34.6° C: Density: 3.214 grams per cubic centimeter: Normal Phase: Gas: Family.
• Atomic number = Number of protons. For example, in a sodium atom, there are 11 electrons and 11 protons. Thus the atomic number of Na atom = number of electrons = number of protons = 11. Atomic Number Orbital Energy Levels. The most common way of showing the arrangement of electrons in an atom is to draw diagrams like those shown in the diagram.
• Chlorine (Cl) exists as a yellow green gas with a pungent smell. It has the atomic number 17 in the periodic table and belongs in Group 17, the Halogens. It is a non metal with the symbol Cl.

The $3 {s}^{2} 3 {p}^{5}$ electrons are the outermost electrons, so chlorine has seven valence electrons.

In a picture, the valence electrons are the ones in the outermost shell.

You can see in the diagram below that there are seven electrons in the outermost circle.

Additionally, a more basic way of determining the number of valence electrons would be to simply look at what group Cl is in.

It is in Group 17, which means it has 7 valence electrons.

Chlorine has an atomic number 17. Atomic number is the number of protons present in the nucleus of an atom. All the atoms of an element have same atomic number. In every stable atom the number of electrons is equal to the number of protons. Therefore, the number of electrons is equal to the number of protons in an chlorine atom. This means, that the number of electrons present in an chlorine atom is 17.

### Atomic Number 17 Indicates The Atom Has

The electronic configuration of chlorine atom is:-
E.C - K L M
2 8 7
Where k, l, ,m are the shells/orbits/ energy levels of an chlorine atom.

Valence electrons are the number of electrons present in the outermost shell of an atom. Now, the last shell of chlorine atom has 7 electrons in it. Therefore, there are 7 valence electrons present in an chlorine atom. Here, stable means that atom has not formed a ion yet.

Ernest Z. · mrpauller.weebly.com

Chlorine has seven valence electrons.

Chlorine has atomic number 17.

The atomic number is the number of protons present in the nucleus of an atom.All the atoms of an element have same atomic number.

In every stable atom the number of electrons is equal to the number of protons. Stable means that atom has not formed a ion yet.

Therefore, the number of electrons is equal to the number of protons in an chlorine atom.

This means, that the number of electrons present in an chlorine atom is 17.

The energy shells of an atom are in the order K, L, M …

So the electronic configuration of chlorine atom is: K, L, M = 2, 8, 7 Valence electrons are the number of electrons present in the outermost shell of an atom.

The last shell of a chlorine atom has 7 electrons in it.

Therefore, there are 7 valence electrons in an chlorine atom.

Here is a video which gives a quick discussion of how to determine how many valence electrons atoms of different elements have.
Video from: Noel Pauller

## Related questions

Also found in: Thesaurus.
 Noun 1 atomic number 17 - a common nonmetallic element belonging to the halogens; best known as a heavy yellow irritating toxic gas; used to purify water and as a bleaching agent and disinfectant; occurs naturally only as a salt (as in sea water)chlorine, Clchemical element, element - any of the more than 100 known substances (of which 92 occur naturally) that cannot be separated into simpler substances and that singly or in combination constitute all mattercommon salt, sodium chloride - a white crystalline solid consisting mainly of sodium chloride (NaCl)gas - a fluid in the gaseous state having neither independent shape nor volume and being able to expand indefinitelyhalogen - any of five related nonmetallic elements (fluorine or chlorine or bromine or iodine or astatine) that are all monovalent and readily form negative ions
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