AQA AS Level Chemistry Paper 1 Exam 2025/2026 Most Recent
Actual Complete Real Exam Questions And Verified Answers |
100% Correct Answers | Graded A+ Guaranteed Success!!
Newest Exam | Just Released!!
Which is the most electronegative element? [1] - ANSWER-
Fluorine
State three factors affecting electronegativity. [3] - ANSWER-
Nuclear charge
(higher= more
electronegative)
Atomic radius (lower=more
electronegative)
Shielding (lower=more
electronegative)
Describe how a polar covalent bond forms. [3] - ANSWER-A
covalent bond
between atoms that differ in
electronegativity.
The shared electrons are pulled closer to the more
electronegative atom,
making it slightly negative and the other atom
slightly positive.
May create a permanent dipole
moment.
,Why do not all polar bonds create a permanent dipole? [1] -
ANSWER-If a molecule multiple polar bonds may cancel each
other out (if they are working in opposite directions)
State the three different intermolecular forces, from weakest to
strongest. [3] -
ANSWER-Van der Waals > Permanent Dipole-Dipole >
Hydrogen Bonding
Describe how permanent Dipole-Dipole forces form. [2] -
ANSWER-Occur between any two molecules with dipole
moments (not necessarily same molecule)
The end of a molecule with a slight positive charge is attracted
to the end of another molecule with a slight negative charge.
Describe how Van der Waals Forces form. [3] - ANSWER-- Van
der Waals forces act between all atoms and molecules at all
time.
- They work in addition to other intermolecular forces.
- The dipole moments are formed by the changing position of
an electron cloud. The larger the electron cloud the greater the
dipole moment can be. Therefore larger molecules (higher Mr)
have stronger Van der Waals.
What criteria must be met for Hydrogen Bonds to form? [2]
Why? - ANSWER-- Molecules are needed in which a Hydrogen
atom is bonded to either Fluorine, Oxygen or Nitrogen
,- Molecules are needed to have at least one lone pair of
electrons. This can be the same type of molecule as the first
or different.
- Must have F-H, O-H or N-H as F, O & N are the most
electronegative elements, and therefore form a very strong
dipole when bonded with H. - When this dipole forms, the
electron on H's outer shell is withdrawn very strongly- leaving
the H atom with almost no electron density and a very strong
δ+ charge on the H.
- Any molecule with a lone pair will have strong attraction to the
δ+ atom.
Why is hydrogen bonding important? - ANSWER-reason why
ice is less dense
than
water
reason for relatively high boiling
point of water
responsible for the double helix
of DNA
Define enthalpy change. - ANSWER-A heat change
measured at constant
pressure
ΔH= enthalpy of products - enthalpy of
reactants
, What does standard conditions imply? [4] - ANSWER-
Pressure 100kPa Temp 298K
Reactants and products in states that are normal under these
conditions.
Any solutions conc 1.0moldm-3
Why are the physical states of the reactants and products
important? [1] -
ANSWER-They affect the enthalpy change of
a reaction.
What occurs in an exothermic reaction? [2] - ANSWER--
Loss/release of energy
- Negative value
of ΔH
What occurs in an endothermic reaction? [2] - ANSWER--
Gain of energy
- Positive value
of ΔH
Define standard enthalpy of formation. [3] - ANSWER--
Enthalpy change when
one mole of a substance is
formed
- From its constituent
elements
Actual Complete Real Exam Questions And Verified Answers |
100% Correct Answers | Graded A+ Guaranteed Success!!
Newest Exam | Just Released!!
Which is the most electronegative element? [1] - ANSWER-
Fluorine
State three factors affecting electronegativity. [3] - ANSWER-
Nuclear charge
(higher= more
electronegative)
Atomic radius (lower=more
electronegative)
Shielding (lower=more
electronegative)
Describe how a polar covalent bond forms. [3] - ANSWER-A
covalent bond
between atoms that differ in
electronegativity.
The shared electrons are pulled closer to the more
electronegative atom,
making it slightly negative and the other atom
slightly positive.
May create a permanent dipole
moment.
,Why do not all polar bonds create a permanent dipole? [1] -
ANSWER-If a molecule multiple polar bonds may cancel each
other out (if they are working in opposite directions)
State the three different intermolecular forces, from weakest to
strongest. [3] -
ANSWER-Van der Waals > Permanent Dipole-Dipole >
Hydrogen Bonding
Describe how permanent Dipole-Dipole forces form. [2] -
ANSWER-Occur between any two molecules with dipole
moments (not necessarily same molecule)
The end of a molecule with a slight positive charge is attracted
to the end of another molecule with a slight negative charge.
Describe how Van der Waals Forces form. [3] - ANSWER-- Van
der Waals forces act between all atoms and molecules at all
time.
- They work in addition to other intermolecular forces.
- The dipole moments are formed by the changing position of
an electron cloud. The larger the electron cloud the greater the
dipole moment can be. Therefore larger molecules (higher Mr)
have stronger Van der Waals.
What criteria must be met for Hydrogen Bonds to form? [2]
Why? - ANSWER-- Molecules are needed in which a Hydrogen
atom is bonded to either Fluorine, Oxygen or Nitrogen
,- Molecules are needed to have at least one lone pair of
electrons. This can be the same type of molecule as the first
or different.
- Must have F-H, O-H or N-H as F, O & N are the most
electronegative elements, and therefore form a very strong
dipole when bonded with H. - When this dipole forms, the
electron on H's outer shell is withdrawn very strongly- leaving
the H atom with almost no electron density and a very strong
δ+ charge on the H.
- Any molecule with a lone pair will have strong attraction to the
δ+ atom.
Why is hydrogen bonding important? - ANSWER-reason why
ice is less dense
than
water
reason for relatively high boiling
point of water
responsible for the double helix
of DNA
Define enthalpy change. - ANSWER-A heat change
measured at constant
pressure
ΔH= enthalpy of products - enthalpy of
reactants
, What does standard conditions imply? [4] - ANSWER-
Pressure 100kPa Temp 298K
Reactants and products in states that are normal under these
conditions.
Any solutions conc 1.0moldm-3
Why are the physical states of the reactants and products
important? [1] -
ANSWER-They affect the enthalpy change of
a reaction.
What occurs in an exothermic reaction? [2] - ANSWER--
Loss/release of energy
- Negative value
of ΔH
What occurs in an endothermic reaction? [2] - ANSWER--
Gain of energy
- Positive value
of ΔH
Define standard enthalpy of formation. [3] - ANSWER--
Enthalpy change when
one mole of a substance is
formed
- From its constituent
elements
