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Notice how in the last example we wrote OH - inside brackets. We do this to indicate that OH - is a complex ion and that there are two of these ions bonded to one calcium ion.

Chemical formulae

  1. Copy and complete the table below:
    Compound Cation Anion Formula
    Na + Cl -
    potassium bromide Br -
    NH 4 + Cl -
    potassium chromate
    potassium permanganate
    calcium phosphate
  2. Write the chemical formula for each of the following compounds:
    1. hydrogen cyanide
    2. carbon dioxide
    3. sodium carbonate
    4. ammonium hydroxide
    5. barium sulphate

Chemical compounds: names and masses

In Giving names and formulae to substances the names of chemical compounds was revised. The relative molecular mass for covalent molecules is simply the sum of the relative atomic masses of each of the individual atoms in that compound. For ionic compounds we use the formula of the compound to work out a relative formula mass. We ignore the fact that there are many molecules linked together to form a crystal lattice. For example NaCl has a relative formula mass of 58 g · mol - 1 .


  • A chemical bond is the physical process that causes atoms and molecules to be attracted together and to be bound in new compounds.
  • Atoms are more reactive , and therefore more likely to bond, when their outer electron orbitals are not full. Atoms are less reactive when these outer orbitals contain the maximum number of electrons. This explains why the noble gases do not combine to form molecules.
  • When atoms bond, electrons are either shared or exchanged.
  • Covalent bonding occurs between the atoms of non-metals and involves a sharing of electrons so that the orbitals of the outermost energy levels in the atoms are filled.
  • The valency of an atom is the number of electrons in the outer shell of that atom and valence electrons are able to form bonds with other atoms.
  • A double or triple bond occurs if there are two or three electron pairs that are shared between the same two atoms.
  • A dative covalent bond is a bond between two atoms in which both the electrons that are shared in the bond come from the same atom.
  • Lewis and Couper notation are two ways of representing molecular structure. In Lewis notation, dots and crosses are used to represent the valence electrons around the central atom. In Couper notation, lines are used to represent the bonds between atoms.
  • An ionic bond occurs between atoms where the difference in electronegativity is greater than 1,7. An exchange of electrons takes place and the atoms are held together by the electrostatic force of attraction between oppositely-charged ions.
  • Ionic solids are arranged in a crystal lattice structure.
  • Ionic compounds have a number of specific properties , including their high melting and boiling points, brittle nature, the lattice structure of solids and the ability of ionic solutions to conduct electricity.
  • A metallic bond is the electrostatic attraction between the positively charged nuclei of metal atoms and the delocalised electrons in the metal.
  • Metals also have a number of properties, including their ability to conduct heat and electricity, their metallic lustre, the fact that they are both malleable and ductile, and their high melting point and density.
  • The valency of atoms, and the way they bond, can be used to determine the chemical formulae of compounds.

End of chapter exercises

  1. Explain the meaning of each of the following terms
    1. Valency
    2. Covalent bond
  2. Which ONE of the following best describes the bond formed between an H + ion and the NH 3 molecule?
    1. Covalent bond
    2. Dative covalent (coordinate covalent) bond
    3. Ionic Bond
    4. Hydrogen Bond
  3. Which of the following reactions will not take place? Explain your answer.
    1. H + H H 2
    2. Ne + Ne Ne 2
    3. Cl + Cl Cl 2
  4. Draw the Lewis structure for each of the following:
    1. calcium
    2. iodine (Hint: Which group is it in? It will be similar to others in that group)
    3. hydrogen bromide ( HBr )
    4. nitrogen dioxide ( NO 2 )
  5. Given the following Lewis structure, where X and Y each represent a different element...
    1. What is the valency of X ?
    2. What is the valency of Y ?
    3. Which elements could X and Y represent?
  6. A molecule of ethane has the formula C 2 H 6 . Which of the following diagrams (Couper notation) accurately represents this molecule?
  7. Potassium dichromate is dissolved in water.
    1. Give the name and chemical formula for each of the ions in solution.
    2. What is the chemical formula for potassium dichromate?

Questions & Answers

where we get a research paper on Nano chemistry....?
Maira Reply
what are the products of Nano chemistry?
Maira Reply
There are lots of products of nano chemistry... Like nano coatings.....carbon fiber.. And lots of others..
Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
no nanotechnology is also a part of physics and maths it requires angle formulas and some pressure regarding concepts
Preparation and Applications of Nanomaterial for Drug Delivery
Hafiz Reply
Application of nanotechnology in medicine
what is variations in raman spectra for nanomaterials
Jyoti Reply
I only see partial conversation and what's the question here!
Crow Reply
what about nanotechnology for water purification
RAW Reply
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
yes that's correct
I think
Nasa has use it in the 60's, copper as water purification in the moon travel.
nanocopper obvius
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
How we are making nano material?
what is a peer
What is meant by 'nano scale'?
What is STMs full form?
scanning tunneling microscope
how nano science is used for hydrophobicity
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
what is differents between GO and RGO?
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
analytical skills graphene is prepared to kill any type viruses .
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
The nanotechnology is as new science, to scale nanometric
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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What makes metals better to use as wires than non-metals? (please link to bonding type)??? HELP
Yash Reply

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Source:  OpenStax, Chemistry grade 10 [caps]. OpenStax CNX. Jun 13, 2011 Download for free at http://cnx.org/content/col11303/1.4
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