BTEC Applied Science Unit 1 Chemistry
exam guide revision with correct answers
How many electrons can an s subshell hold? - ANS 2
How many electrons can a p subshell hold? - ANS 6
How many electrons can a d subshell hold? - ANS 10
Which subshells are available in the first energy level? - ANS s
Which subshells are available in the second energy level? - ANS s and p
Which subshells are available in the third energy level? - ANS s, p and d
What is Hund's rule? - ANS Orbitals must all be singly filled before they can be
doubly occupied
Which elements do not fill the 4s subshell before the 3d subshell? - ANS Copper and
chromium
Define the term ionic bond - ANS The electrostatic attraction between oppositely
charged ions
What is the charge of an ion from group 1? - ANS +1
What is the charge of an ion from group 2? - ANS +2
What is the charge of an ion from group 6? - ANS -2
What is the charge of an ion from group 7? - ANS -1
Explain how atoms of sodium react with atoms of chlorine - ANS Na loses its 2s1
electron gaining a +ve charge.
Cl gains an electron in the 3p subshell gaining a -ve charge.
The opposite charges attract to form NaCl
,Why do ionic bonds have such high melting points? - ANS Each +ve ion is
surrounded by 6 -ve ions and vice versa.
Strong electrostatic attraction in every direction.
Requires a large amount of energy to break
State two factors that affect the strength of an ionic bond - ANS Size of ion and
charge on ion
When can ionic substances conduct electricity? - ANS When molten or in aqueous
solution
Describe the properties of ionic compounds - ANS Conduct electricity when molten
or aqueous solution
High melting/boiling points
Usually soluble in water
Define the term covalent bond - ANS A shared pair of electrons
Which metals lose electrons from the 4s subshell before the 3d subshell? - ANS
Transition metals
Why do metals have such high melting points? - ANS Strong force of attraction
between positive ions and delocalised electrons. This requires a large amount of energy
to overcome.
State the two factors that affect the strength of metallic bonding - ANS Size of ion
Charge on ion
Explain how the charge on metal ions affects the strength of the metallic bond - ANS
The larger the +ve charge the greater the attraction between the nucleus and the
delocalised electrons
Explain how the size of the metal ions affects the strength of the metallic bond - ANS
The smaller the +ve ion the closer the nucleus is to the delocalised electrons creating a
greater attraction
Explain why metals conduct electricity - ANS The delocalised electrons 'carry'
charge. Current flows because of this.
, Explain why metals conduct heat - ANS Particles are paced tightly so kinetic energy
is passed from ion to ion. The delocalised electrons also enable heat to be passed.
Explain why metals are ductile and malleable - ANS The lattice structure allows
layers of metal ions to slide over each other without disrupting bonding
Name the 3 forces between molecules - ANS Van der Waals
Permanent dipole-dipole
Hydrogen bonds
Order the 3 forces between molecules in order of strongest to weakest - ANS
Hydrogen bonds
Permanent dipole-dipole
Van der Waals
How are Van der Waal's forces formed? - ANS Electrons move to one side, caused
temporary dipole. This induces a temporary dipole in neighbouring molecules. Attraction
occurs between oppositely charged dipoles
In what molecules do Van der Waal's forces exist? - ANS Non-polar molecules
How are permanent dipole-dipole forces formed? - ANS Permanent dipole in one
molecule attracts oppositely charged permanent dipole in neighbouring molecule
In which molecules do permanent dipole-dipole forces exist? - ANS Polar molecules
Which elements must be present for hydrogen bonds to exist? - ANS Hydrogen and
either nitrogen, oxygen or fluorine
What is meant by the term displacement? - ANS When a more reactive element
takes the place of a less reactive element in a compound
State the equation for determining moles - ANS Moles = mass ÷ relative atomic
mass (molar mass)
Define the term Avogadro's Constant - ANS The number of atoms in a mole of a
given substance. Quoted as 6.02x10^23
Define the term relative atomic mass - ANS The average mass of an atom of an
element relative to 1/12th the relative atomic mass of Carbon12
exam guide revision with correct answers
How many electrons can an s subshell hold? - ANS 2
How many electrons can a p subshell hold? - ANS 6
How many electrons can a d subshell hold? - ANS 10
Which subshells are available in the first energy level? - ANS s
Which subshells are available in the second energy level? - ANS s and p
Which subshells are available in the third energy level? - ANS s, p and d
What is Hund's rule? - ANS Orbitals must all be singly filled before they can be
doubly occupied
Which elements do not fill the 4s subshell before the 3d subshell? - ANS Copper and
chromium
Define the term ionic bond - ANS The electrostatic attraction between oppositely
charged ions
What is the charge of an ion from group 1? - ANS +1
What is the charge of an ion from group 2? - ANS +2
What is the charge of an ion from group 6? - ANS -2
What is the charge of an ion from group 7? - ANS -1
Explain how atoms of sodium react with atoms of chlorine - ANS Na loses its 2s1
electron gaining a +ve charge.
Cl gains an electron in the 3p subshell gaining a -ve charge.
The opposite charges attract to form NaCl
,Why do ionic bonds have such high melting points? - ANS Each +ve ion is
surrounded by 6 -ve ions and vice versa.
Strong electrostatic attraction in every direction.
Requires a large amount of energy to break
State two factors that affect the strength of an ionic bond - ANS Size of ion and
charge on ion
When can ionic substances conduct electricity? - ANS When molten or in aqueous
solution
Describe the properties of ionic compounds - ANS Conduct electricity when molten
or aqueous solution
High melting/boiling points
Usually soluble in water
Define the term covalent bond - ANS A shared pair of electrons
Which metals lose electrons from the 4s subshell before the 3d subshell? - ANS
Transition metals
Why do metals have such high melting points? - ANS Strong force of attraction
between positive ions and delocalised electrons. This requires a large amount of energy
to overcome.
State the two factors that affect the strength of metallic bonding - ANS Size of ion
Charge on ion
Explain how the charge on metal ions affects the strength of the metallic bond - ANS
The larger the +ve charge the greater the attraction between the nucleus and the
delocalised electrons
Explain how the size of the metal ions affects the strength of the metallic bond - ANS
The smaller the +ve ion the closer the nucleus is to the delocalised electrons creating a
greater attraction
Explain why metals conduct electricity - ANS The delocalised electrons 'carry'
charge. Current flows because of this.
, Explain why metals conduct heat - ANS Particles are paced tightly so kinetic energy
is passed from ion to ion. The delocalised electrons also enable heat to be passed.
Explain why metals are ductile and malleable - ANS The lattice structure allows
layers of metal ions to slide over each other without disrupting bonding
Name the 3 forces between molecules - ANS Van der Waals
Permanent dipole-dipole
Hydrogen bonds
Order the 3 forces between molecules in order of strongest to weakest - ANS
Hydrogen bonds
Permanent dipole-dipole
Van der Waals
How are Van der Waal's forces formed? - ANS Electrons move to one side, caused
temporary dipole. This induces a temporary dipole in neighbouring molecules. Attraction
occurs between oppositely charged dipoles
In what molecules do Van der Waal's forces exist? - ANS Non-polar molecules
How are permanent dipole-dipole forces formed? - ANS Permanent dipole in one
molecule attracts oppositely charged permanent dipole in neighbouring molecule
In which molecules do permanent dipole-dipole forces exist? - ANS Polar molecules
Which elements must be present for hydrogen bonds to exist? - ANS Hydrogen and
either nitrogen, oxygen or fluorine
What is meant by the term displacement? - ANS When a more reactive element
takes the place of a less reactive element in a compound
State the equation for determining moles - ANS Moles = mass ÷ relative atomic
mass (molar mass)
Define the term Avogadro's Constant - ANS The number of atoms in a mole of a
given substance. Quoted as 6.02x10^23
Define the term relative atomic mass - ANS The average mass of an atom of an
element relative to 1/12th the relative atomic mass of Carbon12
