Electron bonding and structure

Define electron pair repulsion theory ?

• The shape of the molecule is determined by the electron pair surrounding the central atom

• This is based on the fact that pairs of electrons repel each other

What is the effect of lone pairs on the shape of molecule?

• Lone pairs reduce the bonding angle by 2.5

• Lone pairs repel more strongly

What happens when electron repel each other ?

-They move further away

Describe and draw a linear molecule

• 2 Bonding pairs

• 180

Describe and draw a trigonal planar

• 3 bonded pairs

• 120

Describe and draw a octahedral

• 6 Bonding pairs

• 90

Describe and draw a tetrahedron

• 4 bonding pairs

• 109.5

Describe and draw a triangular pyramid

• 3 bonded pairs

• 1 lone pair

• 107

Describe and draw a non-linear

• 2 Bonded pairs

• 2 lone pairs

• 104.5

Define ionic bonding

The electrostatic force of attraction between opposite charge ions

Describe the structure of sodium chloride

• Ions are packed closely together forming a lattice

• Each ion is electrostatically attracted in all directions to ions of opposite charge

What are the properties of ionic compounds?

• They conduct electricity when they are molten or dissolved

• They have high melting and boiling point

Why do ionic compounds dissolve ?

• Water molecules are polar so interact with the ionic compound

• The ions are pulled away from the lattice

What is a molecule?

• A group of atoms bonded together held by covalent bonds

What is a covalent bond?

• Is the electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atoms?

State the three main rules for electron configurations

• A single energy orbital is filled fast

• For orbitals with the same energy electrons occupy orbitals singly with the same spin before pairing begins

Why is the 4S orbital filled in first than the 3d orbital?

• 4S has a lower energy level than 3d

What is an orbital ?

• A region of space and electron moves in

Describe and state the three orbitals ?

• S orbitals are spherical

• P orbitals are a dumbbell shaped

• D orbitals

Define an intermolecular force?

• They are forces between molecules

What is the strongest type of intermolecular force?

• Hydrogen bonds

How does a hydrogen bond form?

• When hydrogen is covalent bonded to fluorine nitrogen and oxygen

• Weak bonds form between the hydrogen atom of one molecule and a loan pair of electrons on the other molecule.

Why is water less dense in ice form?

• Ice has hydrogen bonds then liquid

• Hydrogen bonds are relatively long

• Resulting in the molecules being further apart

State the two properties of hydrogen bonds

• They are soluble in water

• They have high melting and boiling points

What are the two properties of simple covalent bonds?

• Have low melting and boiling points

• They don’t conduct electricity

Describe in disciple dipole interactions

• Dipoles can cause another induced dipole the two dipoles holeare then attracted to each other

What causes an induced dipole dipole interaction?

• Electrons in charge clouds travel quickly

What causes a stronger induced dipole dipole?

• Larger molecules because they have larger electron clouds

• Molecules with greater surface areas because they have a bigger exposed

What are the properties with molecules with stronger induced dipole dip?

• High boiling point

Describe a permanent dipole?

• Form on polar molecules

• They cause electrostatic forces of attraction between molecules

• It’s cause in addition to induced dipole dipole interactions

Define electronegativity ?

• A atoms ability to attract the electron pair in a covalent bond

What the trends in electronegativity in the periodic table ?

• Electronegativity increases across

• Electronegativity decreases down groups

Define ionic bonding

• The electrostatic force of attraction between positively charged ions and negatively charged ions