The simply answer is that in the outer shell each of the halogens have only seven electrons, this is the reason why they are the most reactive nonmetals, they wish to require a further electron to become stable.
Fluorine (F) Atomic number 9 [He] 2s22p5 note the second shell is the outer shell and has only 7 electrons, to be stable it has to have eight.
Chlorine (Cl) Atomic number 17 [Ne] 3s23p5 note this its the third shell which is the outer shell and has only 7 electrons, to be stable it has to have eight.
For Bromine (Br) we find its the fourth shell is the outer shell which has seven elections, and finally Iodine (I) we find its the fifth shell which is the outer shell and it has only 7 electrons, to be stable it has to have eight.
Hope this helps
5.
You can find this in any Periodic Table, just look at the last number in the Noble Gas Configuration, and make sure it is the same for the whole group.
Halogen bulbs are sensitive to oils in the human hand so you should always wear latex gloves or use something to cover your hand or the bulb will no longer function once you turn it on. Halogen bulbs are commonly used in dance club lighting and when i DJ'd i'd have to keep some gloves handy.
Its called the electron shell. Electrons will always fill up low orbitals first in the shell, an then as more energy is added to the atom, the electrons move up an orbit, then release the energy in some form, and they move back down to the lowest energy orbit.
An element, as opposed to a compound or mixture.
The whole number, the one at the top, above the element's symbol in the element box, is the atomic number. The atomic number is the number of protons per atom in that particular element. The bottom number, that is always a decimal, is the atomic mass.
Calcium atoms have the electronic configuration 2,8,8,2 so they react by losing 2 electrons. Chlorine is 2,8,7 so picks up one electron. Therefore each calcium ion is formed in conjunction with two chloride ions. The calcium ions are positively charged, and the chlorides are negative so the substance is held together by electrostatic attraction. This process is called ionic bonding.
Astatine, the always radioactive one.
Astatine, the always radioactive one.
102 ( the atomic #, # of protons, and #of electrons are always the same )
Barium loses electrons to obtain a stable octet, like any other metal.
A noble gas atom has a completely full outer shell of electrons. Noble gases almost always exist as single atom molecules, rarely bonding with other atoms. Other element's electron configurations are often expressed by the closest lower numbered Noble gas, then just showing the additional electron shells on top of that configuration, rather than showing the entire electron shell configuration of the element.
1s 2 2s 2 2p6 3s2 3p6 4s2 or Ar 4s2 (Noble gas form) In noble gas form, you go back to the noble gas (the last group on the Periodic Table) prior to the element you are writing the configuration for. The electron configuration is the same up until that point. Then you write down the difference. In this example, the electron configuration for Argon (Ar) is 1s2 2s2 2p6 3s2 3p6. If you fill up the shells until 4s2, you get calcium. It's faster to abbreviate by saying "Ar 4s2"
The number of Electrons is always the same as the number of Protons.The number of Protons is the "Atomic Number" in the Periodic Table.The element with Atomic Number 7 is Nitrogen (N).Nitrogen is at the top of Group 15 in the Periodic Table.See related link below.
atoms in stable compounds almost always have a noble gas electron configuration or when representative metals and nonmetals react, thay transferelectrons in such a way that both th cation and the anion have noble gas electron configuration.
The activity of any element depends on the number of electrons it has in its outer energy level, called valence electrons. Atoms in group one, metals have only one electron in their outer energy level, instead of two so they have incomplete outer energy levels; they are always looking to lose or share their electron with another atom to complete their outer energy level and become more stable. In contrast, the noble gases have complete outer energy levels so they do not interact with other elements. Thus, knowing the electron configuration enables you to determine the valence electrons and predict the reactivity of an element.
A potassium atom "always" loses exactly one valence electron when it reacts with another element, because one valence electron in a potassium atom has a much lower ionization energy requirement than any other electron in the same atom. (This property is generally ascribed to the fact that when a potassium loses exactly one electron, it acquires the very stable electron configuration of the noble gas argon.) A chlorine atom has a very strong attraction (its electronegativity) for exactly one electron, which gives the charged atom the electron configuration of an argon atom. Therefore, when a potassium atom is close enough to a chlorine atom, one electron is transferred between to form an ionic bond and a formula unit of the compound potassium chloride.
In Lewis Dot Diagrams, there should always be a dot for the elements. You can only go up so high before you get into other aspects like electron configuration. If there are no dots then you likely need to draw them.
The number of PROTONs and the number of ELECTRONs are always equal in a neutral atom. Therefore an element with one PROTON will have one ELECTRON and that element will be called Hydrogen.