Bonding Flashcards
Why do bonds form?
To achieve a more stable electron arrangement.
What does ionic bonding occur between?
Metals and non-metals.
Where are the electrons transferred in an ionic bond and why?
From the metals to the non-metals because metals have few electrons in their outer level so easily lose them.
What forces attract the two ions formed from an ionic bond?
Electrostatic forces of attraction between oppositely charged ions.
What is the structure called that ionic compounds exist in?
A lattice
Name three properties of an ionic compound?
Solids at room temperate, have a high melting point because a lot over energy is required to overcome the forces of attraction between ions. Conduct electricity when molten and are brittle because if positive and positive charges meet they repel.
What does a covalent bond form between?
Two non-metals which share a pair of electrons.
Why don’t the molecules in a covalent bond have a charge?
No electrons have been transferred.
How does the sharing of electrons hold the molecules together?
Electrostatic attraction between the nucleus of the molecule and the shared electrons.
How many electrons are shared in a double covalent bond?
4
Why can molecules in a covalent bond not conduct electricity?
There are no ion to conduct the charge.
What is a coordinate bond?
One in which one atom donates both of the electrons to be shared.
Why are metals good conductors of electricity?
Delocalised electrons which can move freely through out the structure.
What does the strenth of a metal depend on?
The charge on the ion (more delocalised electrons- stronger the electrostatic attraction) and the size of the ion (smaller - closer to the nucleus - stronger).
What is electronegativity?
The power of an atom to attract the electron density in a covalent bond towards itself.
What does electronegativity depend on?
The nuclear charge, the distance between the nucleus and the outer electrons and the shielding of nuclear charge by inner electrons.
What are the most electronegative atoms?
Nitrogen, oxygen and fluorine.
Name three types of intermolecular forces
Van der Waals forces, dipole-dipole and hyfrogen bonding.
What do van der Waals forces increase with?
The number of electrons present, so bioling points increase with an increased atomic number or chain length.
What conditions need to be present for hydrogen bonding to occur?
A very electronegative atom with a lone pair of electrons covalently bonded to a hydrogen atom.
What is electron pair repulsion theory?
Electron pairs will repel other pairs so they take up positions as far away from each other as possible to minimise repulsion.
What is enthalpy?
The heat energy change measured under constant pressure.
What are the four basic crystal types?
Ionic, metallic, molecular and macromolecular.
What are the differences between macromolecular and molecular crystals?
Macromolecular crystals have covalent bonds throughout the compound while in molecular crystals the bonds are between the atoms in the molecule not between molecules. Macromolecular has a much higher boiling point because of this.
