AS Chemistry Unit 1: Equations and Formulae

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What do the terms RAM and RFM stand for in the context of chemical compounds?

Radial atomic mass and radial formula mass

Relative atomic model and relative formation mass

Relative atomic mass and relative formula mass (correct)

Relative analysis mass and relative functional mass

How is the formula for calculating the amount of moles (n) in a solid derived?

n = RFM * mass(g)

n = mass(g) * RFM

n = mass(g) / RFM (correct)

n = RFM / mass(g)

What does Avogadro's constant represent?

The number of atoms in 1 gram of any element

The amount of energy in 1 mole of a gas

The number of molecules in 1 mole of a substance (correct)

The mass of one mole of carbon-12

In the equation $Cu + S \rightarrow CuS$, how many moles of each element are reacting?

1 mole of Cu and 1 mole of S Signup and view all the answers

If you have 2.71g of carbon dioxide (CO2), what is the relative formula mass (RFM) you should use for calculations?

44 g/mol Signup and view all the answers

Which statement correctly describes the final equation presented?

It shows a displacement reaction. Signup and view all the answers

What is indicated by the term 'molar mass'?

The mass of one mole of a substance Signup and view all the answers

What happens to the oxidation state of magnesium when it reacts and forms $Mg^{2+}$?

It increases Signup and view all the answers

What distinguishes isotopes from each other?

Different mass number Signup and view all the answers

What is the purpose of a mass spectrometer?

To determine the mass of atoms and molecules Signup and view all the answers

In a mass spectrum graph, what does the horizontal axis represent?

Mass measurement Signup and view all the answers

How many peaks would you expect from the mass spectrum of a diatomic element like chlorine?

5 Signup and view all the answers

What is implied about the ions analyzed in a mass spectrometer?

They all have a single positive charge Signup and view all the answers

Why is the peak corresponding to 35Cl larger than that for 37Cl in the mass spectrum?

35Cl naturally occurs in a higher ratio Signup and view all the answers

Which of the following species produces a peak at m/z 70 in the mass spectrum of chlorine?

[35Cl-37Cl]+ Signup and view all the answers

What does the vertical axis in a mass spectrum graph typically represent?

Relative abundance or percentage abundance Signup and view all the answers

If a mass spectrometer is used on an element, what will it show?

Spectrum with masses and relative abundances for all isotopes Signup and view all the answers

Which of the following correctly describes the ions in a mass spectrometer?

They have only positively charged ions Signup and view all the answers

What describes water of crystallisation in a chemical compound?

Water chemically bonded to a salt in the crystal structure Signup and view all the answers

What is the first step in determining the degree of hydration?

Finding the mass of the anhydrous salt and the mass of water lost Signup and view all the answers

Which subatomic particle has a positive charge?

Proton Signup and view all the answers

How would you find the moles of water lost during the reaction?

Divide the mass of water lost by the relative formula mass (RFM) of water Signup and view all the answers

What does the atomic number of an element represent?

Number of protons in the nucleus of an atom Signup and view all the answers

Which of the following describes an anhydrous salt?

A salt obtained after heating a hydrated salt to remove water Signup and view all the answers

What is the relative mass of a neutron compared to a proton?

Neutrons and protons have the same relative mass Signup and view all the answers

How do you obtain the ratio of anhydrous salt to water from moles?

Divide the moles of both substances by the moles of anhydrous salt Signup and view all the answers

What is the relative atomic mass (RAM) of an element calculated relative to?

One-twelfth of the mass of an atom of carbon-12 Signup and view all the answers

Which process is involved in transforming a hydrated salt into an anhydrous salt?

Heating Signup and view all the answers

What is the first ionisation energy of an element?

Energy required to convert 1 mol of gaseous atoms into gaseous ions with a single positive charge Signup and view all the answers

Which factor does NOT influence changes in ionisation energy across a period?

Number of electrons in the outer shell Signup and view all the answers

What happens to the ionisation energy as you move down a group in the periodic table?

It decreases due to increased atomic radius and shielding Signup and view all the answers

How are electrons represented when filling subshells?

As arrows pointing up and down to indicate spin Signup and view all the answers

Which subshell contains the most orbitals?

4f Signup and view all the answers

What is the equation representing second ionisation energy?

X+(g) → X2+(g) + e- Signup and view all the answers

What trend in ionisation energy occurs across a period?

Generally increases with some decreases Signup and view all the answers

Which statement about electron pairing in subshells is accurate?

Electrons pair only when no unfilled orbitals are available Signup and view all the answers

What is the characteristic of ionisation energies regarding their energy values?

They are endothermic processes measured in kJ/mol Signup and view all the answers

What explains the hardness of metallic structures?

Strong attraction between positive ions and negative electrons Signup and view all the answers

Why do metals usually have high melting points?

Strong metallic bonds require much energy to break Signup and view all the answers

What is the primary reason for good electrical conductivity in metals?

Localized electrons that can move and carry charge Signup and view all the answers

What allows metals to exhibit ductility?

Layers of positive ions sliding over each other Signup and view all the answers

Which metal has a higher melting point due to its electron configuration?

Magnesium with two delocalized electrons Signup and view all the answers

What defines an ionic compound's structure?

Ionic lattice of oppositely charged ions Signup and view all the answers

What identifies a simple anion in ionic compounds?

They end in -ide suffix Signup and view all the answers

Which statement about metallic bonds is true?

Metallic bonds are stronger when there are more delocalized electrons Signup and view all the answers

What is the correct order in which subshells fill with electrons?

1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p Signup and view all the answers

Which element has the SPD notation 1s²2s²2p⁶3s¹?

Sodium Signup and view all the answers

What happens to the energy levels when losing electrons from an atom?

Electrons are lost from the highest numbered orbitals first. Signup and view all the answers

Which of the following statements about transition metals is true?

They lose their 4s electrons before their 3d electrons. Signup and view all the answers

What indicates that an atom is in the d-block of the periodic table?

Outer electrons in the d-subshell Signup and view all the answers

What is the ground state configuration of an atom?

Configuration where electrons are in their lowest available energy levels Signup and view all the answers

Which element is an exception to the usual electron configuration rules?

Copper Signup and view all the answers

How can you determine the electronic configuration of an ion?

By writing the atom’s normal configuration and then adding/removing electrons Signup and view all the answers

What aspect makes half-filled or completely filled p or d-orbitals more stable?

They have a lower overall energy and increased stability Signup and view all the answers

Which of the following is true regarding the electron filling order in atomic orbitals?

Electrons fill from lowest to highest energy levels Signup and view all the answers

What notation is used to represent the electronic configuration visually?

Electrons-in-box diagrams Signup and view all the answers

What is the correct configuration for Aluminium?

1s²2s²2p⁶3s²3p¹ Signup and view all the answers

Which of the following correctly describes the 3d subshell of transition metals?

It contains outermost electrons for many transition metals. Signup and view all the answers

In which order do electrons fill the orbitals closest to the nucleus?

In order of increasing energy levels, starting from the nucleus Signup and view all the answers

Study Notes

AS Chemistry Unit 1: Formulae, Equations and Amounts of Substance

Ionic Names and Formulae: "ate" ions have the highest number of oxygens, "ite" ions have fewer. Diatomic elements of group 7 include Fluorine (F), Bromine (Br), Iodine (I), Oxygen (O), Nitrogen (N), Chlorine (Cl), and Hydrogen (H). Examples include Sulfate (SO₄^2-), Sulfite (SO₃^2-), Nitrate (NO₃^-), Nitrite (NO₂^-), and Phosphate (PO₄^3-).

Writing and Balancing Chemical Equations

Ionic Equations: Begin with the overall equation. Separate aqueous ionic compounds into their constituent ions. Keep insoluble and covalent compounds as they are. Cross out spectator ions (ions that appear on both sides). Example: CuSO₄(aq) + Mg(s) → MgSO₄(aq) + Cu(s) becomes Cu²⁺(aq) + SO₄^2-(aq) + Mg(s) → Mg²⁺(aq) + SO₄^2-(aq) + Cu(s). After cancelling spectator ions, the net ionic equation is Cu²⁺(aq) + Mg(s) → Mg²⁺(aq) + Cu(s).

RAM, RMM, RFM and Molar Mass

RAM: Relative atomic mass (used for elements).
RMM: Relative molecular mass (used for molecular compounds).
RFM: Relative formula mass (used for ionic compounds).
Molar Mass (MM): Mass of one mole of a substance. Calculating RFM involves adding the RAMs of all atoms in the compound.

The Mole

Avogadro's Constant: The number of atoms in 12.000 g of carbon-12. Approximately 6.02 x 10²³.
Mole: The amount of substance containing Avogadro's constant number of atoms, molecules, or groups of ions.

Calculating Moles (Solids)

Formula: moles = mass (g) / RFM
Example: Calculate the moles in 2.71 g of carbon dioxide (CO₂): moles = 2.71 g / 44 g/mol = 0.0616 mol.

Calculating Moles (Solutions)

Formula: moles = volume (cm³) x concentration (mol/dm³) / 1000
Note: Volume is usually given in cm³; convert to dm³ by dividing by 1000.

Limiting Reactants and Excess Reactants

Limiting Reactant: Reactant that limits product formation in a reaction (runs out first).
Excess Reactant: Reactant that remains after the limiting reactant is consumed.
Calculations: Use the balanced equation to find the limiting reactant. Convert the given masses to moles, then compare moles of reactants using the mole ratios to determine the limiting reactant.

Water of Crystallisation

Water of Crystallisation: Water chemically bonded within a crystal structure.
Anhydrous Salt: Salt that does not contain water of crystallisation.
Calculations: Find the mass of the anhydrous salt and water lost, find moles of anhydrous salt and water, divide moles of anhydrous and water by the moles of anhydrous salt to get the ratio of anhydrous salt to water, which is degree of hydrate.

Atomic Structure

Atoms: Composed of protons, neutrons, and electrons.
Subatomic Particles: Relative mass and charge.

Atomic Number (Z)

Number of protons in an atom.

Mass Number (A)

Sum of protons and neutrons in an atom.

Relative Atomic Mass (RAM)

Average mass of the isotopes of an element relative to 1/12th the mass of carbon-12.

Relative Isotopic Mass (RIM)

Mass of an isotope relative to 1/12th the mass of carbon-12.

Relative Formula Mass (RFM)

Average mass of a formula unit relative to one-twelfth of the mass of an atom of carbon-12.

Relative Molecular Mass (RMM)

Average mass of a molecule relative to one-twelfth of the mass of an atom of carbon-12.

Mass Spectrometry

Mass Spectrometry: Technique used to determine the mass of atoms or molecules by ionizing samples and determining their mass-to-charge ratios.
Mass Spectrum: Plot of relative abundance versus mass-to-charge ratio, which can identify isotopes of elements or compounds.
Molecular Ion Peak: Peak in the spectrum corresponding to the molecular ion, showing the RMM.
Fragments: Products formed when a compound or element ionizes and breaks up into smaller fragments, revealing their structure.

Electronic Configuration

Energy Levels ("n"): Electrons occupy different energy levels, starting with the lowest energy levels closest to the nucleus.
**Subshells (s, p, d, f):**Energy levels subdivided into subshells which are collections of orbitals. s orbitals are spherical, p orbitals are dumbbell-shaped, d orbitals are more complex shapes.
Orbitals: Regions within an atom where an electron is likely to be found
Max electrons in subshells: s holds 2, p holds 6, d holds 10, and f holds 14
Electronic configuration of atoms and ions: Shows the arrangement of electrons in energy levels and subshells. This shows the filling order; 1s 2s 2p 3s 3p 4s 3d 4p...

Ionisation Energy

Ionisation Energy: Energy needed to remove an electron from a gaseous atom or ion.
First Ionisation Energy: Energy to remove the first electron.
Successive Ionisation Energies: Energy required to remove additional electrons.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

Test your knowledge of ionic names, formulas, and balancing chemical equations in AS Chemistry Unit 1. This quiz covers key concepts such as 'ate' and 'ite' ions, as well as how to write and balance ionic equations effectively. Perfect for students preparing for their exams!