National 5 Chemistry (UNIT 1) Flashcards
Answer the questions (exam style), then look at the answers. The number of marks is not given, just write everything you can down for the question. This covers ALL the mandatory knowledge of unit 1.
State how the progress of a chemical reaction can be measured.
- Changes in mass
- Changes in volume
- Changes in other quantities
Describe how the rate of reaction can be increased.
- Increase the temperature
- Increase the concentration of a reactant
- Increasing the surface area
- Decrease particle size
- Use a catalyst
State what is meant by the term ‘catalyst’.
A catalyst is a substance that speeds up a chemical reaction but can be recovered chemically unchanged at the end of the reaction.
Over the course of a 5 minute reaction, 50g of CaC03 was lost. Calculate the rate of reaction showing appropriate units.
0.167 gs-1
Use the rate equation in the data booklet.
You must show the units in this question.
Describe how the rate of a reaction can be shown to decrease over time.
Calculate the average rate at different stages of the reaction.
Describe how elements in the Periodic Table are arranged.
- In order of increasing atomic number.
Is magnesium a metal? Justify your answer.
Magnesium is a metal as it is on the left of the periodic table.
What do elements in the same group have in common?
The same number of electrons in their outer energy levels. (outer electrons)
What is the electron arrangement of hydrogen?
1
State the charges on the sub-atomic particles of an atom.
Proton - 1+
Neutron - 0
Electron - 1-
State the mass on the sub-atomic particles of an atom.
Proton - 1 amu
Neutron - 1 amu
Electron - 0 amu
Fill in the gap:
In a neutral atom, the number of _____ is equal to the number of _____.
Proton/Electron (any order)
Fill in the gap:
The mass number of an atom is equal to the number of _____ added to the number of _____.
Proton/Neutron (any order)
State what is meant by the term ‘isotope’.
An atom with the same atomic number but different mass number/ same number of protons but different number of neutrons.
State what is shown by nuclide notation for an ion.
- Mass number
- Atomic number
- Charge
State what is meant by the term ‘relative atomic mass’.
- The average atomic mass for an element using the mass and proportion of each isotope for that element.
Is the statement true or false:
Covalent bonds form between non-metal atoms.
True
Explain how a covalent bond forms.
A covalent bond forms when two positive nuclei are held together by their common attraction for a shared pair of electrons.
Draw a diagram showing all the outer electrons for NH3.
- Any diagram (petal diagram included) is suitable.
State the diatomic molecules.
Use: Have No Fear Of Ice Cold Beer.
- Hydrogen
- Nitrogen
- Fluorine
- Oxygen
- Iodine
- Chlorine
- Bromine
State the four shapes of simple covalent molecules.
- Linear
- Angular
- Trigonal pyramidal
- Tetrahedral
True or false:
Only one bond can be formed between atoms.
False
More than one bond can form, leading to double or triple covalent bonds.
State the two types of covalent substances.
- Discrete covalent molecular
- Covalent networks
Explain the properties of covalent molecular substances.
- They have strong covalent bonds within the molecules and only weak attractions between the molecules.
- They have low melting and boiling points as only weak forces of attraction between the molecules are broken when a substance changes state.
- They do not conduct electricity because they do not have charged particles which are free to move.
True or false:
Covalent molecular substances which are insoluble in water may dissolve in other solvents.
True.
What is the difference between covalent molecular and covalent network substances in terms of bonding?
- Covalent molecular substances have weak intermolecular bonds but strong covalent bonds within the molecule.
- Covalent network substances only have a strong network of covalent bonds within one giant structure.
Fill in the gaps:
Covalent network structures have very _____ melting and boiling points because the network of strong _____ _____ is not easily _____.
High/Covalent/Bonds/Broken
True or false
Covalent network substances do not dissolve
True.
Explain why covalent network substances do not conduct electricity.
- They do not have charged particles which are free to move. (DO NOT ACCEPT ‘ions’)
Name one covalent substance which conducts electricity. Explain why this is the case.
- Graphite/Carbon because it has a sea of delocalised electrons, like metals, which are free to move.
Explain how ions are formed.
Ions are formed when atoms lose or gain electrons to obtain the stable arrangement of a noble gas/a full outer electron shell.
State the charge on a metal ion.
Positive.
State the name of an equation to show the formation of ions through the loss or gain of electrons.
Ion-electron equations.
State what is meant by the term ‘ionic bond’.
- Ionic bonds are the electrostatic attraction between positive and negative ions.
State the term used to describe the structure of an ionic compound.
Lattice.
Explain the properties of ionic compounds.
- They have high melting and boiling points because strong ionic bonds must be broken in order to break the lattice.
- They are soluble in water as the lattice structure breaks up allowing water molecules to surround the separated ions.
- They conduct electricity when molten or in solution as the lattice structure breaks up allowing the ions to be free to move.
State the elements present in copper sulfate.
- Copper
- Sulfur
- Oxygen
Write the chemical formulae for copper nitrate.
Cu(NO3)2
What do roman numerals indicate about an element?
Its valency.
Fill in the gap:
The formula of a _____ _____ and any _____ substance gives the simplest ratio of each type of atom in a substance.
- Covalent network
- Ionic
State the name of ions which contain more than one type of atom.
Group ions.
Balance the following equation:
H2+O2 -) H2O
the numbers should be small
2H2 + O2 -) 2H20
The 2 in front of the hydrogens are big and the 2 behind the oxygen and hydrogen in water are small.
What is the percentage composition of nitrogen in ammonia?
82.2%
Working:
NH3
GFM = (14+1+1+1) = 17g
(14/17 x 100) = 82.2%
True or false:
pH 7 is an acid.
False. It is a neutral solution.
Write down the equation showing how water dissociates.
Correct ‘disassociation of water’ balanced equation.
True or false:
The disassociation of water is reversible.
True.
Describe the difference in terms of H+ and OH- ions between pH 1, 7, 9.
- pH 1 has a higher concentration of H+ ions than OH- ions.
pH 7 has equal concentrations of H+ and OH- ions.
pH 9 has higher concentrations of OH- ions than H+ ions.
Fill in the gaps:
Dilution of an alkaline solution with water will _____ the concentration of OH- ions and the pH will decrease towards pH __.
- Decrease
- 7
Describe how acidic solutions are formed.
Soluble non-metal oxides dissolve in water.
What term could be used to describe the following:
- Metal oxides
- Metal hydroxides
- Metal carbonates
- Ammonia
Bases
What is always produced in a neutralisation reaction?
a salt and water.
What type of salt does hydrochloric acid produce?
chloride salts.
State what is meant by the term ‘spectator ion’.
Ions that remain unchanged by the reaction.
Open ended question practice: (3 marks)
Using your knowledge of chemistry, explain how the concentration of a specific acid can be determined.
Possible things to mention:
(response should cover at least 1 A4 page, with info, equations, drawings etc.)
- Acid-base titration (drawing and description)
- Standard solutions
- Concordant values
- n=CV
- Balanced equations
- Mole ratios
- Indicators
- Pipettes/burettes
- Sample calculation
Describe the preparation of a soluble salt.
- Do a titration. Once the volumes of acid and alkali have been noted, repeat the neutralisation reaction without indicator and evaporate the solution to dryness.
OR - Insoluble metal carbonates and insoluble metal oxides can be added to acids, filtered and the filtrate can be evaporated to dryness.
