The external electron shell is responsible for the formation of chemical bonds.
by covalent and ionic bonding
by covalent and ionic bonding
The Bohr model of the atom places electrons in orbits or "shells." Elements in the first period only have electrons in the first shell. Elements in the second period have electrons in the first two shells. Elements in the third period have electrons in the first three shells, and so on.
A group of elements that rarely combine with other elements because they already have eight electrons in the outer shells is a Noble Gas
Electron shells
Yes they have eight electrons in their valence shells. This is why they are not reactive. All elements have valence shells.
The table was organized so that elements of similar properties are in the same group. What (partly) determines reactivity is the number of electrons an atom has in it's ground state. . Within the atom electrons are organized in shells. Atoms are stable when they have 8 electrons in their outer shell (for hydrogen and helium it is 2 electrons.) . Elements of: Group 18 have 8 electrons in their outer shells Group 17 have 7 electrons in their outer shells Group 16 have 6 electrons in their outer shells Group 15 have 5 electrons in their outer shells Group 14 have 4 electrons in their outer shells Group 13 have 3 electrons in their outer shells Groups 3-12 have varied number of electrons in their outer shells Group 2 have 2 electrons in their outer shells Group 1 have 1 electron in their outer shells
The atomic numbers of the elements down a group increase. this means, more electrons. More electrons mean more shells. More shells mean larger radius. Larger radius is nothing but larger size. Thus, the number of electrons or shells is the reason why the size of the atom of elements increase down the group.
Groups are the number of outer shell electrons in the elements and periods are the number of outer shells in the elements. eg. group 4, period 3 is Silicon which means that it has 3 shells where the electrons are stored and in the last shell it has 4 electrons
All thed block elements (except d10) have this tendency.
There are no difference in the number of shells in magnesium and sulphur. Both elements contain 3 shells. However, the total number of electrons in the shells are different. Magnesium has 12 electrons in its shells whereas sulphur has 16 electrons in its shell. In addition, the electrons in the valence shell (outermost shell) are also different. Magnesium has 2 electrons in its valence shell whereas sulphur has 6 electrons in its valence shell.
Its elemental weight
The shell model explains the organization of the periodic table. The elements in the first period have electrons in the first shell; the elements in the second period have electrons in the first two shells; the elements in the third period have electrons in the first three shells; and so on.
Valence electrons are the ones which participate in chemical reactions in some way, either by moving from one atom to another, or by being shared with another atom. They are found in the outer shell of an atom (there are usually inner shells with other electrons that are not valence electrons, although in the lightest elements, there are no inner shells and all electrons are valence electrons).