Hydrogen how many valence electrons

How many valence electrons does hydrogen have? Chemistry Electron Configuration Valence Electrons. Ernest Z. Apr 15, Hydrogen has 1 valence electron. Explanation: Hydrogen is in the first row of the Periodic Table.

Hydrogen has only one electron, so that electron is a valence electron. Example How many electrons does helium have? Solution Helium is also in the first row of the Periodic Table. It is filling its 1s orbital. Today we shall take up the topic of Hydrogen Valence Electrons. Valency is an important concept in chemistry and has been used to formulate many theories in chemistry and science in general. It can be found by looking at the group number of an element in a periodic table.

Since Hydrogen has only one electron in its shell, its valency is 1. It can also find out by looking at the periodic table since Hydrogen belongs to group 1. Recall that a polyatomic ion is a group of atoms that are covalently bonded together and which carry an overall electrical charge. When drawing the Lewis structure of a polyatomic ion, the charge of the ion is reflected in the number of total valence electrons in the structure.

In the case of the ammonium ion:. It is customary to put the Lewis structure of a polyatomic ion into a large set of brackets, with the charge of the ion as a superscript outside the brackets. As important and useful as the octet rule is in chemical bonding, there are some well-known violations.

This does not mean that the octet rule is useless—quite the contrary. As with many rules, there are exceptions, or violations. There are three violations to the octet rule. Odd-electron molecules represent the first violation to the octet rule. Although they are few, some stable compounds have an odd number of electrons in their valence shells.

With an odd number of electrons, at least one atom in the molecule will have to violate the octet rule. The Lewis electron dot diagram for NO is as follows:. Although the O atom has an octet of electrons, the N atom has only seven electrons in its valence shell. Although NO is a stable compound, it is very chemically reactive, as are most other odd-electron compounds. Electron-deficient molecules represent the second violation to the octet rule. These stable compounds have less than eight electrons around an atom in the molecule.

The most common examples are the covalent compounds of beryllium and boron. For example, beryllium can form two covalent bonds, resulting in only four electrons in its valence shell:. Boron commonly makes only three covalent bonds, resulting in only six valence electrons around the B atom. A well-known example is BF 3 :. The third violation to the octet rule is found in those compounds with more than eight electrons assigned to their valence shell.

These are called expanded valence shell molecules. Such compounds are formed only by central atoms in the third row of the periodic table or beyond that have empty d orbitals in their valence shells that can participate in covalent bonding. One such compound is PF 5. The only reasonable Lewis electron dot diagram for this compound has the P atom making five covalent bonds:. Identify each violation to the octet rule by drawing a Lewis electron dot diagram.

A Lewis electron dot diagram for this molecule is as follows:. In SF 6 , the central S atom makes six covalent bonds to the six surrounding F atoms, so it is an expanded valence shell molecule. Its Lewis electron dot diagram is as follows:.

Identify the violation to the octet rule in XeF 2 by drawing a Lewis electron dot diagram.