Science - 2018-19

CH.3 a, c-d - Chemical Bonding

The student will investigate and understand how conservation of energy and matter is expressed in chemical formulas and balanced equations. Key concepts include:
a) nomenclature; 

c) writing chemical formulas; and

d) bonding types.

Bloom's Levels:  Analyze; Understand

Adopted: 2010

BIG IDEAS

  • Chemical bonding occurs as a result of attractive forces between particles.

  • I can identify the chemicals in my shampoo.
  • I can determine what substances are in my food.

UNDERSTANDING THE STANDARD

  • Chemical formulas are used to represent compounds. Subscripts represent the relative number of each type of atom in a molecule or formula unit. The International Union of Pure and Applied Chemistry (IUPAC) system is used for naming compounds.
  • When pairs of elements form two or more compounds, the masses of one element that combine with a fixed mass of the other element form simple, whole-number ratios (Law of Multiple Proportions).
  • Compounds have different properties than the elements from which they are composed.
  • The empirical formula shows the simplest whole-number ratio in which the atoms of the elements are present in the compound. The molecular formula shows the actual number of atoms of each element in one molecule of the substance. 
  • Lewis dot diagrams are used to represent valence electrons in an element. Structural formulas show the arrangements of atoms and bonds in a molecule and are represented by Lewis dot structures.
  • Bonds form between atoms to achieve stability. Covalent bonds involve the sharing of electrons between atoms. Ionic bonds involve the transfer of electrons between ions.Elements with low ionization energy form positive ions (cations) easily. Elements with high ionization energy form negative ions (anions) easily. Polar bonds form between elements with very different electronegativities. Non-polar bonds form between elements with similar electronegativities.
  • Polar molecules result when electrons are distributed unequally.

ESSENTIALS

In order to meet this standard, it is expected that students will

a)  name binary covalent/molecular compounds.

     name binary ionic compounds (using the Roman numeral system where appropriate).

c)  predict, draw, and name molecular shapes (bent, linear, trigonal planar, tetrahedral, and trigonal pyramidal).

     write the chemical formulas for certain common substances, such as ammonia, water, carbon monoxide, carbon dioxide, sulfur dioxide, and carbon tetrafluoride.

     use polyatomic ions for naming and writing formulas of ionic compounds, including carbonate, sulfate, nitrate, hydroxide, phosphate, and ammonium.

     use valence shell electron pair repulsion (VSEPR) model to draw and name molecular shapes (bent, linear, trigonal planar, tetrahedral, and trigonal pyramidal).

     recognize polar molecules and non-polar molecules.

d)  draw Lewis dot diagrams to represent valence electrons in elements and draw Lewis dot structures to show covalent bonding.

KEY VOCABULARY

alloy, anion, cation, chemical bond, delocalized electrons, electrolyte, electron sea model, formula unit, ionic bond, lattic energy, metallid bond, monatomic ion, oxidation number, oxyanion, polyatomic ion, coordinate covalent bond, covalent bond, endothermic,exothermic, hybridization, Lewis structure, molecule, oxyacid, pi bond, polar covalent, resonance, sigma bond, structural formula, VSEPR model


Updated: Dec 04, 2017