(BCR) Bonding and Chemical Reactions Module Overview

Bonding and Chemical Reactions Module Overview

Toothpaste, eggs, car

Did you know that chemical reactions are a part of your everyday life? Every time you cook food or drive your car, the results are due to bonding and chemical reactions. Do you like action-packed movies? Without chemical reactions, the special effects would not be very spectacular. In this module, you will learn how atoms bond together, what happens in a chemical reaction, and how to write chemical formulas and name compounds. Be prepared to watch some amazing chemical reactions along the way as well.

Essential Questions

  • Why and how do atoms form chemical bonds with each other?
  • How are chemical changes represented?
  • How does scientific understanding support the statement that "there is nothing new under the sun"?
  • How are compounds named?
  • How do you determine a chemical formula?

Key Terms

  1. Chemical bond - a region that forms when valence electrons from different atoms interact with each other.
  2. Valence electrons - an electron located in the outermost shell (valence shell) of the atom, that can be transferred to or shared with another atom.
  3. Ionic bond – bond formed by the transferring of electrons. Occurs between a metal (loses electrons) and a nonmetal (gains electrons).
  4. Ion - an electrically charged atom due to losing or gaining 1 or more electrons.
  5. Cation – a positively charged ion due to the loss of 1 or more electrons.
  6. Anion – a negatively charged ion due to gaining 1 or more electrons.
  7. Octet Rule - a rule stating that atoms lose, gain, or share electrons in order to have 8 valence electrons.
  8. Oxidation number - numerical charge of an ion that indicates the number of electrons lost, gained, or shared. For example, a +1 means an atom lost 1 electron whereas a -3 means an atom gained 3 electrons.
  9. Subscript – written below the line to indicate the number of atoms.
  10. Superscript – written above the line to indicate the charge (oxidation number) of the ion.
  11. Polyatomic ions - a covalently bonded group of atoms that usually forms ionic bonds with other atoms. Common examples include PO4-3, SO4-2, NO3-1, CO3-2, OH-1, NH4+1.
  12. Covalent bond – bond formed by the sharing of electrons. Occurs between two nonmetals.
  13. Molecule - a group of atoms bonded together, representing the smallest fundamental unit of a chemical compound that can take part in a chemical reaction.
  14. Polar bond – type of covalent bond in which the electrons are not being shared equally. This results in one end of the molecule having a slightly negative charge and the other a slightly positive charge.
  15. Nonpolar bond – type of covalent bond in which the electrons are being shared equally.
  16. Prefix – a word added in the front of another word. Prefixes are used in naming covalent compounds.
  17. IUPAC - acronym of International Union of Pure and Applied Chemistry. An organization that establishes official names of chemical elements and compounds.
  18. Chemical reaction – a chemical change that results in the rearrangement of atoms forming products with new properties.
  19. Product – a substance that is the result of a chemical change and is written on the right side of the arrow in a chemical equation.
  20. Reactant – a substance that undergoes a chemical change and is written on the left side of the arrow in a chemical equation.
  21. Law of Conservation of Matter – a law stating that matter is neither created nor destroyed. In a chemical reaction, the same number of atoms occurs in the products as in the original reactants.
  22. Chemical equation - a way to describe what goes on in a chemical reaction, the actual change in a material.
  23. Coefficient – the number placed in front of molecules in a chemical equation that represents the number of molecules.
  24. Combustion reaction – type of chemical reaction in which a compound and oxygen are combined to produce heat and a new product. Example: 2H2 + O2 → 2H2O
  25. Synthesis – type of chemical in which two or more simple substances combine to form a more complex substance. General equation: A + B → AB Example: 8 Fe + S8 → 8 FeS
  26. Decomposition – a type of chemical reaction in which a more complex substance breaks down into its more simple parts. General equation: AB → A + B Example: 2 H2O → 2 H2 + O2
  27. Single replacement - a type of chemical reaction in which a single uncombined element replaces another in a compound. General equation: A + BC → AC + B Example: Zn + 2HCl → H2 + ZnCl2 Double Replacement – A type of chemical reaction in which parts of two compounds switch places to form two new compounds. General Equation: AB + CD → AD + CB Example: NaCl + LiBr → NaBr + LiCl
  28. Exothermic reactions - a chemical reaction that releases energy in the form of light or heat. Usually feels hot to the touch. Heat is released because more energy is required to break apart the bonds of the reactants than to form the product.
  29. Endothermic reactions - a chemical reaction accompanied by the absorption of heat. Usually feels cold to the touch. Energy is absorbed from the surrounding environment because more energy is required to form the product than it is to break apart the bonds of the reactants.

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