An element with atomic number 18 is a noble gas. Into which family you shall place elements with atomic number 17 and 19 and why?

Explanation:

An element with atomic number 18 is a noble gas.

The element with atomic number 19 will have one extra electron so it can donate one electron or shed one electron to attain noble gas configuration .

It tends to shed one electron to become positively charged ion . Hence they are electro-positive elements .  

Similarly the element with atomic number 17 will have one short  electron so it can gain  one electron  to attain noble gas configuration .

They  tend to gain  one electron to become negatively charged ion . Hence they are electro-negative  elements . They have high  electronegativity .

answer: the primary difference between a hypothesis and a theory is that b hypothesis is falsifiable, but a theory has been proven to be correct. theory is an explanation of something that is happening but hypothesis is a guess of something that can happen

explanation:

assuming that your periodic table has eighteen columns, you should highlight   the four elements in the third column from the left of the table.

neutral atoms of elements after calcium contain d electrons. the energy of d orbitals of a particular main shell lies between the energy of the s and p orbitals of the next main shell. for example, electrons in the have energy higher than those in the orbital while lower than those of the orbital.

by the aufbau principle, electrons fill orbitals one at a time, starting from those of the lowest energy. the orbital is therefore filled right after orbitals and before orbitals.  

potassium has electron configuration and calcium . the s orbital of a main shell holds a maximum of two electrons. the next element would thus have the electron configuration and satisfy the requirements.

a neutral atom of the element contains three electrons on top of the most recent noble gas element. it should thus be placed in the third column of the periodic table. both scandium and yttrium would satisfy the conditions. an aufbau diagram indicates that the 4f orbital is filled before the 5d. however, it appears that exceptions exists for both lanthanum and actinium. neutral atoms of the two d-block elements also demonstrate the and should be highlighted as well.