Question

 Model 2: Compound formation

 Atoms can form ions when donating or accepting valence electrons to or from another atom. These ions are held together by strong electrical interactions between opposite charges, called an lonic bond, and thus forming a neutral compound.

 Critical Thinking Questions:

 8. How many electrons did lithium donate? How many did bromine accept?

 9. Based on the electron configuration, which noble gas does lithium now resemble?

 10. Based on the electron configuration, which noble gas does bromide now resemble?

 11. Both the lithium ion and the bromide ion have charges. What is the net (total) charge on

 the compound (LiBr) that is formed in Figure 2? Ensure that all team members

 understand how you arrived at this answer.

 12.a. An oxygen atom can lose or galn (circle one) two electrons to achieve a noble gas configuration.

 b. How many electrons will this oxygen ion have?How many protons?

 c. What will be the charge on this oxygen ion?

 d. Following the examples of Li* and Br" in Figure 2, write the symbol for the ion formed from an oxygen atom..

 e. Based on the electron configuration, which noble gas does an oxygen ion resemble?

 13. Lithium can also form compounds with oxygen. Work with your team and determine which of the three formulas shown below would represent the neutral compound that would be formed. Circle your choice, and explain why you chose it.

 LiO Li₂O LiO₂

Answer 1

The atoms will donate or accept electrons to achieve noble gas Configuration and thereby becomes the ions these ions are electrostatically attracted and forming an ionic bonded neutral molecule.

Q.8)

the atomic number of lithium = 3

electronic configuration = 2(k shell) , 1(L shell) (1s², 2s¹)

number of valence electrons = 1

there is one electron in the valence orbital hence lithium will try to loose this valence electron by donating it to another atom and becomes Li⁺ , thereby achieve noble gas configuration.

the atomic number of bromine = 35

electronic configuration = 1s²,2s²,2p⁶,3s²,3p⁶,3d¹⁰,4s²,4p⁵ (2,8,18,7)

number of valence electrons = 7

bromine has 7 valence electrons therefore for bromine accepting one electron is easier than donating 7 electrons hence bromine will accept one electron to get nearby stable noble gas configuration and become Br^-

Q.9)

electronic configuration of lithium after donating one electron = 2(k shell) (1s²)

which resembles the noble gas Helium (atomic number 2)

Q.10)

electronic configuration of Bromine after accepting one electron = 1s²,2s²,2p⁶,3s²,3p⁶,3d¹⁰,4s²,4p⁶

which resembles the noble gas krypton (atomic number = 36, electronic configuration = 1s²,2s²,2p⁶,3s²,3p⁶,3d¹⁰,4s²,4p⁶)

Q.11)

Li⁺ have one positive charge and Br^- have one negative charge these ions will electrostatically attract and form LiBr. the total charge of this compound is zero.  LiBr is a neutral compound. both the ions have equal but opposite charge it contribute towards strong ionic bond formation and cancel out equal and opposite charges. while forming ionic bond total number of electrons becomes equal to total number of electrons hence the total charge becomes zero.

total number of protons in LiBr = 3 +35 = 38

total number of electrons in LiBr = 2 + 36 = 38

Q.12)

(a)

the atomic number of oxygen = 8

electronic configuration = 1s²,2s²,2p⁴(2,6)

number of valence electrons = 6

oxygen have 6 valence electrons hence for oxygen, accepting 2 electrons are more easier than donating the 6. hence oxygen accept 2 electrons to become O^2-

(b)

after accepting 2 electrons oxygen becomes O^2- it have, total, 10 electrons = 8 (already have) + 2(got by accepting)

number protons in oxygen = 8 (proton have + charge hence +8 charge)

number of electrons in oxygen = 8 (electron is - vely charged hence -8 charge)

therefore total zero charge

in the case of oxygen ion, O^2-,

number protons in oxygen ion = 8 ( +8 charge)

number of electrons in oxygen ion  = 10 ( -10 charge)

hence total charge = -2 (charge of oxygen ion)

in the formation of ion only the electrons as losted or gained, which does not alter the number of protons present in it.

(c)

if an atomaccept electrons it is indicated by negative charge, here oxygen accept 2 electron to become oxygen ion hence it have a negative charge.

(d)

the ion formed from the oxygen is,  O^2-

(e)

electronic Configuration of oxygen ion = 1s²,2s²,2p⁶(2,8)

which resembles the electronic configuration of Neon (atomic number =10, electronic Configuration of oxygen ion = 1s²,2s²,2p⁶(2,8))

Q.13)

as above mentioned lithium have 1 valence electron hence it will try to lose this electron to become Li+ , whereas oxygen have a deficiency of 2 electron to get noble gas configuration. hence two lithium atoms must contribute towards the oxygen atom. hence the resultant neutral compound will be Li₂O.

charge of one lithium ion = +1

total charge of two lithium ions = +2

charge of one oxygen ion = -2

total charge of Li₂O = +2-2 = 0

In LiO there is Li have +1 charge and oxygen have +2 charge hence net charge can not be zero

also in LiO₂ charge of one lithium ion is +1 and total charge of two oxygen ions are +4 hence net charge can not be zero.