Modeling Chemical Bonding

Chemical Bonding: Ionic & Convalent

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What we will cover today

• Definition of a chemical bond

• Difference between ionic and covalent bonds

• How to write chemical formula

What is a chemical bond?

• atoms are rarely found on their own

• bonding occurs when valence shell electrons interact together

• when atoms of different elements are bonded to each other it is called a compound

• they occur because atoms want to be STABLE with a FULL outer shell

Multiple Choice

What type of bonding does this picture show?

• Ionic

• Covalent

Multiple Choice

What type of bonding does this picture show?

• Ionic

• Covalent

Ionic Bonding

• complete transfer of electrons

• metal + non-metal

• very strong bonds

• 'balancing out' of the charges between the atoms

How to write ionic formula:

• 1. Determine the ionic charge of the metal and non-metal atoms

• 2. Drop and swap the charges

• 3. Check the charges are balanced!

Covalent Bonding

• sharing of electrons

  • they both need to gain electrons ​

• between non-metal + non-metal

• we draw Lewis dot diagrams to display these bonds

• again, it's all about forming a full valence shell - a full octet

Multiple Choice

Which of these element pairs would bond covalently?

• Fr and K

• Sc and O

• F and Cl

• He and Pt

How to write a covalent formula:

• 1. Determine how many electrons each atom needs to be considered stable

• 2. ​Determine how each of the atoms will share the electrons

• 3. Draw the ​electron-dot structure

• 4. Write formula ​

Drawing a Lewis dot diagram: Covalent

• 1. Draw out the number of electrons on the valence shell for each atom

• 2. Determine how many electrons the atoms need to make a full outer shell

• 3. Re-draw them as bonded (this is a double bond)

Drawing a Lewis dot diagram: Ionic

• 1. Draw out the number of electrons on the valence shell for each atom

• 2. Determine how many electrons the atoms need to make a full outer shell

• 3. Re-draw them with transferred electrons/bonded

• 4. Input charges and brackets ​

Naming compounds:

• ionic = name of the metal + name of the non-metal with suffix -ide

• covalent = number of atoms prefix+element name + number of atoms prefix+element with -ide root

Multiple Choice

The chemical bond between a metal and a non-metal will be a _____ bond.

• metal

• ionic

• covalent

• polar

Multiple Choice

What is the formula for diphosphorus pentoxide?

• P₂O₅

• PO₅

• P₅O₂

• P₂O₆

Multiple Choice

What is the correct name for NO?

• Mononitrogen Monoxide
• Nitrogen Monoxide
• Mononitrogen Dioxide
• Nitrogen Oxide

Multiple Choice

Which formula is for phosphorus trichloride?

• KCl₃

• PCl₃

• K₃Cl

• P₃Cl

Multiple Choice

Lead Chloride is an ionic compound, made up from Pb²⁺ ions and Cl^- ions. Which is the correct formula for this compound?

• PbCl₃

• PbCl

• PbCl₄

• PbCl₂

Multiple Choice

Magnesium Hydroxide is an ionic compound made up from Mg²⁺ and OH^- ions. Which is its correct formula?

• MgOH

• MgOH₂

• Mg(OH)₂

• MgO

​Transition Metals and Variable Charges:

​You might see in some questions that there are roman numerals​ in brackets after an element symbol OR there is a transition metal of which you are unsure of the charge. There are two rules about this:

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1. If there is a roman numeral, this is the ionic charge of the atom

2. If there is no roman numeral, you assume the ionic charge i​s 2+

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Ti(III) = Ti³⁺

Mn = ​Mn²⁺

Open Ended

What questions do you have about this content? I will answer them quickly now, or will do so next lesson :)