Counting Atoms, Balancing Equations, Ionic and Covalent Bonding

Introduction

Having listened to your teacher's explanation on Counting Atoms, please review the video to receive further information on Counting Atoms and Molecular formulas.

[video:https://www.youtube.com/watch?v=m87TFcMSfQ8 align:center]

Proceed to the Process screen to practice Counting Atoms, Balancing Equations, & Ionic and Covalent Bonding.

Process

Evaluation

Please take the quiz on counting atoms.

Counting Atoms Quiz

Conclusion

The Law of Conservation of Mass is observed in a balanced chemical equation, which is a chemical equation that shows all mass is conserved throughout the reaction.  

In a balanced equation the reactants the products will both have the same mass.  This means that in a chemical reaction, matter is neither created nor destroyed, a concept discovered by Antoine Lavoisier in about 1785.

Example:  2H2 + O2----> 2H2O, thre reactants of H2 and O2 equal the product of 2H2O.  Also see the image below: the reaction between Sodium Hydroxide(aq) and Copper Sulfate(aq).

Counting Atoms and Balancing Equations

Chemical reactions are a way of chemical equations. For example, when hydrogen, H2, burns, it reacts with oxygen, O2, in the air to form water, H2O. The chemical equation for this reaction follows:

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The chemical formulas on the left of the arrow represent the reactants. The substances produced in the reaction are called products, are shown to the right of the arrow. The numbers in front of the formulas are coefficients; this tells you the number of molecules. The subscript tells you the number of atoms in front of it. for example H2, says there are two Hydrogen atoms.

Ionic and Covalent Bonding

Ionic Bonding

Ionic bonds form between metals and nonmetals.  Metals are the elements on the left side of the Periodic table.  Metals tend to lose electrons to attain Noble Gas electron configuration.  Groups 1 and 2 (the active metals) lose 1 and 2 valence electrons, respectively..  Non-metals are limited to the elements in the upper right hand corner of the Periodic Table.  The most non-metallic element is fluorine.  Nonmetals tend to gain electrons to attain Noble Gas configurations.  The have relatively high Electron affinities.

Metals tend to lose electrons and nonmetals tend to gain electrons, so in reactions involving these two groups, there is electron transfer from the metal to the non-metal.   

Covalent Bonding

Covalent bonding takes place between non-metals.  There is no transfer of electrons, but a sharing of valence electrons.  The non-metals all have fairly high ionization energies, meaning that it is relatively difficult to remove their valence electrons.  The non-metals also have relatively high electron affinities, so they tend to attract electrons to themselves.  So, they share valence electrons with other nonmetals.  The shared electrons are held between the two nuclei.  

In the next unit we will learn about Energy

Energy can be transformed into different forms just like compounds and atoms can have their bonds broken and rearranged into something new. 

The process of energy transformation is also known as energy conversion.  The Law of Conservation of Energy states that: energy cannot be created nor can it be destroyed.    This means the total amount of energy ALWAYS stays the same.

 
The main energy forms are:

  • radiant (light) energy
  • chemical energy
  • mechanical energy
  • nuclear energy
  • electrical energy
  • heat (thermal) energy
  • energy of sound

Credits