Chemical Bonding ☹️ Flashcards
Which is smaller - mass number or atomic number?
Atomic number
Define isotopes
Atoms of the same element with same number of protons but different number of neutrons
What properties do isotopes of the same element have
They are the same as they have the same amount of electrons
How do ionic compounds bond
By losing or gaining electrons to make a full shell
( draw the one with square brackets )
What ions do metals generally form and what are they called?
+ve ions
Cations
What ions do non-metals generally form and what are they called?
-ve ions
Anions
How are +ve and -ve ions held together?
Strongly, by electrostatic forces of attraction in a giant lattice
Why do ionic substances have high melting and boiling points?
Strong electrostatic forces of attraction between oppositely charged ions throughout giant structure require lots of heat energy to break
Why are ionic substances hard but brittle?
Strong forces of electrostatic attraction, but layers can slide, and when ions of same charge align, the structure breaks
Why are ionic substances generally soluble in water?
Ions are attracted to polar water molecules, and this attraction breaks the lattice apart
Why do ionic substances NOT conduct electricity in solid state?
Charged ions are held in position and are not free to move
Why do ionic substances conduct electricity when liquid (or dissolved in solution)
The charged ions are free to move
How do covalent compounds bind?
They share a pair of electrons by donating electrons to the shared pair
They then have the same structure as noble gases
Covalent bonds are sometimes also called molecular bonds
What are the two types of covalent?
Simple molecular
Giant covalent
What are simple molecular?
Made up of tiny molecules which contain multiple atoms held together by covalent bonds
What are giant covalent?
They contain millions of atoms bonded together by MANY strong covalent bonds to form a giant molecule, or macromolecule
E.g graphite and diamond
Fun fact cos I can’t think of a question for this
Covalent bonds can share two or three electron pairs too
Why do simple covalent substances have low melting and boiling points?
Because there are only weak intermolecular forces between molecules, these only need little heat energy to overcome
Why do simple covalent substances have poor electrical conductivity?
There are no charged ions or free electrons present
Why are simple molecular substances poorly soluble in water?
There are no charged particles present to be attracted to polar water molecules
How do you draw a dot and cross diagram for covalent substances
Like a Venn diagram yk
Why can giant covalent substances have such different properties?
Because each atom can be bonded to a different amount of other atoms
Diamond - bonded to 4 others
Graphite - bonded to 3 others
But both are carbon
What is the structure of diamond?
Each carbon atom covalently bonded to 4 others
Why is the melting point of diamond so high?
MANY strong covalent bonds require lots of heat energy to break
