Calcium atom 20 e-
Ca2+ 18 e-
When it becomes an ion it is loosing electrons causing the effective nuclear charge to increase which draws the remaining electrons in closer which makes the ion smaller than the atom.
Technically, any atom could have 40 electrons, but it would have a very weird charge. However, Zirconium has 40 electrons without being an ion.
The calcium atom (Ca) loses two valence electrons to form a calcium ion (Ca2+).
The radius of a cadmium atom is smaller than the radium of a mercury atom. The trend for atomic radius is that the radius becomes larger toward the left side of the row and toward the bottom of the group.
Depends on what you mean by number of electrons. Calcium has 20 electrons and oxygen has 8 electrons for a total of 28 electrons. But if you mean how many VALENCE electrons, then the calcium has 2 and the O has 6 for a total of 8 valence electrons.
It loses 2 electrons.
Calcium, as an element, has 20 electrons. But when becomes an ion, it loses two electrons, becoming Ca+2. Therefore, as an ion, calcium has only 18 electrons.18
calcium forms Ca+2 ion having 18 electrons which are equal to the electrons of noble gas Argon.
20 (any more or less and it would be an ion not an atom)
When it becomes an ion it is loosing electrons causing the effective nuclear charge to increase which draws the remaining electrons in closer which makes the ion smaller than the atom.
Technically, any atom could have 40 electrons, but it would have a very weird charge. However, Zirconium has 40 electrons without being an ion.
The calcium atom (Ca) loses two valence electrons to form a calcium ion (Ca2+).
They are the same in that they have the same number of protons and neutrons. However, the number of electrons is different. The calcium 2+ ion has two less electrons than the normal calcium atom.
a negative ion
The radius of a cadmium atom is smaller than the radium of a mercury atom. The trend for atomic radius is that the radius becomes larger toward the left side of the row and toward the bottom of the group.
There are 7 valence electrons in chlorine atom and 8 valence electrons in chloride ion.
The ionic charge is +2: The atom has equal numbers of positively charged protons and negatively charged electrons. The number of protons is the same in the atom and the ion, but in the ion two negative charges have been lost, so that the ion has a net charge of +2.