chemical bonding

• Electronegativity is the ability of an atom to attract a pair of electrons towards itself in a covalent bond.
• The phenomenon of electronegativity arises from the positive nucleus’s ability to attract the negatively charged electrons, in the outer shells, towards itself.
• The Pauling scale is used to assign a value of electronegativity for each atom.
• Fluorine is the most electronegative atom on the Periodic Table, with a value of 4.0 on the Pauling Scale.
• Fluorine is best at attracting electron density towards itself when covalently bonded to another atom.
• Nuclear charge exists between the positively charged protons in the nucleus and negatively charged electrons found in the energy levels of an atom.
• An increase in the number of protons leads to an increase in nuclear attraction for the electrons in the outer shells.
• An increased nuclear charge results in an increased electronegativity.
• As the nuclear charge increases, the electronegativity of an element increases as well.
• The atomic radius is the distance between the nucleus and electrons in the outermost shell.
• Electrons closer to the nucleus are more strongly attracted towards its positive nucleus.
• Those electrons further away from the nucleus are less strongly attracted towards the nucleus.
• Electron pairs repel each other as they have similar charges.
• Molecules can adopt the following shapes and bond angles: Molecules of different shapes can adopt different bond angles.
• Electrons are negatively charged and will repel other electrons when close to each other.
• Different types of electron pairs have different repulsive forces.
• Answer 1: The shape of a molecule can be determined using VSEPR theory.
• Examples of molecules with different shapes and bond angles include: Worked example: VSEPR & shapes of molecules.
• Lone pair electrons repel each other more than bonded pairs.
• Answer 2:The bond angles of a molecule can be determined using VSEPR theory.
• Answer 3:Examples of molecules with different shapes and bond angles include:
• The valence shell electron pair repulsion theory (VSEPR) predicts the shape and bond angles of molecules.
• The most stable shape is adopted to minimize the repulsion forces.
• In a molecule, the bonding pair of electrons will repel other electrons around the central atom, forcing the molecule to adopt a shape in which these repulsive forces are minimised.
• Repulsion between multiple and single bonds is treated the same as for repulsion between single bonds.
• Repulsion between pairs of double bonds are greater.
• When determining the shape and bond angles of a molecule, the following VSEPR rules should be considered: Valence shell electrons are those electrons that are found in the outer shell.
• An increased atomic radius results in a decreased electronegativity.
• Solids are denser than their liquids as the particles in solids are more closely packed together than in their liquid state.
• When two atoms in a covalent bond have the same electronegativity, the covalent bond is nonpolar, with the bonding electrons shared equally between the two atoms.
• The surface molecules are pulled downwards due to the hydrogen bonds with other molecules, whereas the inner water molecules are pulled in all directions.
• Ice floats on water because of ice's lower density.
• Electronegativity is the ability of an atom to draw a pair of electrons towards itself in a covalent bond, which increases across a Period and decreases going down a Group.
• The less electronegative atom in a polar bond gets a partial charge of δ+ (delta positive), while the more electronegative atom gets a partial charge of δ- (delta negative).
• When two atoms in a covalent bond have different electronegativities, the covalent bond is polar and the electrons will be drawn towards the more electronegative atom, resulting in an asymmetric electron distribution.
• The greater the difference in electronegativity, the more polar the bond becomes.
• The ‘more open’ structure of molecules in ice causes it to have a lower density than liquid water.
• Water molecules at the surface of liquid are bonded to other water molecules through hydrogen bonds, causing the surface molecules to become compressed and more tightly together, increasing water’s surface tension.
• In ice, the water molecules are packed in a 3D hydrogen-bonded network in a rigid lattice, with each oxygen atom surrounded by hydrogen atoms.
• The electronegativity values are equal resulting in the formation of a nonpolar covalent bond.