T4 Chemical Bonding

• Chemical bonds form when atoms lose, accept, or even share electrons with each other.
• Compound formation via chemical bonds keeps atoms stable. Some compounds, including

  those that form a diatomic bond with themselves (i.e. hydrogen, oxygen, sulfur, chlorine, and

  nitrogen among others), can only become stable when they have a "complete octet", where

  each atom of each element has a total of eight (8) atoms!
• CHEMICAL BONDING

  Chemical bonds form when atoms lose, accept, or even share electrons with each other.

  • Most atoms that exist only by themselves are less stable compared to when they are bonded

  with other atoms in a compound.
• The Pauling scale is the most commonly used (Linus Pauling).

  The higher the electronegativity of an element, the more that atom will attempt to pull electrons

  towards itself and away from any atom it bonds to.

  A) electronegativity

  
• REASONS FOR ELECTRONEGATIVITY

  • Number of Protons
  • Distance from the Nucleus
  • Screening by the electrons
• 1. Electronegativity DECREASES down a group because electrons that occupy higher energy levels

  are easier to remove because they are farther from the nucleus.

  2. Electronegativity INCREASES across a period because As protons are added across a period, the

  electrons are harder to remove because the nucleus is pulling them with greater force.
• Covalent bonds do not generally share electrons equally among the participating atoms. Those that do are known as nonpolar-covalent bonds. Examples of this bond are hydrogen diatoms (H2), oxygen (O2), carbon dioxide (CO2), and nitric oxide (NO). The ones that do not share electrons equally are called polar covalent bonds because these molecules form a polar charge that results from one (1) element holding on the shared electrons longer than the other participant elements. Examples of this bond are iodine chloride

  (ICl), water (H2O), ammonia (NH3 ), and hydrogen fluoride (HF).
•  an ionic bond happens when one atom transfers an electron to another. The result is two ions with opposite charges that attract each other. Classic examples are the bonds found in sodium chloride (table salt).
• a method

  A) lewis dot structure

  
• Polar Covalent bond- the unequal sharing of electrons between two atoms.

  • are asymmetric, either containing lone pairs of electrons on a central atom

  or having atoms with different electronegativities bonded.

  A) polarity

  
• Polar bond is formed when there is a difference between the

  electronegativity values of the atoms participating in the bond.
• Non Polar Covalent bond- the equal sharing of electrons between two

  atoms.

  • will be symmetric, meaning all of the sides around the central atom

  are identical - bonded to the same element with no unshared pairs of

  electrons

  • are formed when there is a similar in the electronegativity values of the atoms in the participating bond.
• Classification of bonds can be determined by calculating the difference in

  the electronegativity values between the elements.

  A) nonpolar

  B) polar

  C) ionic

  
• type of bond

  A) hydrogen bond

  
• properties of hydrogen bonding

  
• • (Molecular structure) The study of the three-dimensional arrangement of the atoms that

  constitute a molecule
• • Understanding the molecular structure of a compound can help determine the polarity,

  reactivity, phase of matter, color, magnetism, as well as the biological activity.
• Valence Shell Electron Pair Repulsion Theory

  • states that electron pairs repel each other whether or not they are in bond pairs or in lonepairs. Thus, electron pairs will spread themselves as far from each other as possible to minimize repulsion. it focuses not only on electron pairs, but it also focus on electron groups as a whole.
• Valence Shell Electron Pair Repulsion Theory: An electron group can be an electron pair, a lone pair, a single unpaired electron, a double bond or a triple bond on the center atom. Using the VSEPR theory, the electron bond pairs and lone pairs on the center atom will help us predict the shape of a molecule.
• Molecular geometric

  A) linear

  B) trigonal planar

  C) bent

  D) tetrahedral

  
• Molecular Geometry

  A) trigonal pyramidal

  B) bent

  C) trigonal bipyramidal

  D) octahedral