how many electrons does each group lose or gain?
In the main group, the common valence is the same as the group number.
To determine how many electrons each group gains or loses, you need to look at the periodic table and identify the group number of the element in question.
For the main group elements, the group number of an element represents the number of valence electrons it has. Valence electrons are the electrons in the outermost energy level or shell of an atom.
The main group elements consist of the groups 1, 2, and 13 to 18 on the periodic table. In these groups, the number of valence electrons determines the element's chemical properties and reactivity.
In a neutral atom, the number of electrons is equal to the number of protons (which is the atomic number). Therefore, to find the number of electrons gained or lost by an element in the main group, you can subtract the group number from either 8 or 18, depending on the period.
For example:
- Group 1 elements (e.g., hydrogen, lithium, sodium) have one valence electron, so they tend to lose one electron to achieve a stable electron configuration.
- Group 2 elements (e.g., beryllium, magnesium, calcium) have two valence electrons, so they tend to lose two electrons.
- Group 17 elements (e.g., fluorine, chlorine, bromine) have seven valence electrons, so they tend to gain one electron to achieve a stable configuration by filling their outermost shell.
- Group 18 elements (e.g., helium, neon, argon) already have a full outer electron shell, consisting of 8 electrons (except for helium, which has 2). Therefore, they do not tend to lose or gain electrons.
It's important to note that these are general trends, and there can be exceptions and variations based on specific elements and compounds.