Atomic Structure and Fundamental Particles

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Questions and Answers

What is the overall charge of an atom's nucleus?

Variable

Negative

Positive (correct)

Neutral

Which model describes the atom as a small, dense central nucleus surrounded by orbiting electrons?

Electron Shell Model (correct)

Rutherford Model

Plum Pudding Model

Quantum Mechanical Model

What is the maximum number of electrons that can occupy the second shell of an atom?

8 (correct)

What do protons, neutrons, and electrons all have in common?

They all contribute to the mass of the atom Signup and view all the answers

How is mass number calculated for an atom?

Sum of protons and neutrons Signup and view all the answers

What is the relative mass of an electron compared to protons and neutrons?

1/1840 Signup and view all the answers

In a neutral atom, what must be true about the number of protons and electrons?

Number of protons equals number of electrons Signup and view all the answers

What particle(s) contribute to the overall positive charge of the nucleus?

Protons only Signup and view all the answers

What is relative atomic mass defined as?

The mean mass of an atom of an element divided by one twelfth of carbon-12's mean mass. Signup and view all the answers

Which statement about isotopes is correct?

Isotopes possess the same atomic number but different mass numbers. Signup and view all the answers

What happens when an atom forms an ion?

It loses or gains electrons, creating a charged atom. Signup and view all the answers

What is the purpose of mass spectrometry?

To identify different isotopes and determine relative atomic mass. Signup and view all the answers

During the ionisation stage of Time of Flight (TOF) mass spectrometry, what occurs?

High voltage is applied to remove electrons, forming positive ions. Signup and view all the answers

What factor does not affect the path of ions in mass spectrometry during ion drift?

The initial temperature of the sample Signup and view all the answers

Which of the following statements regarding the physical properties of isotopes is true?

Isotopes can differ in physical properties due to varying mass numbers. Signup and view all the answers

What effect does gaining electrons have on an atom?

The atom becomes a negatively charged ion. Signup and view all the answers

Which orbital can hold a maximum of 10 electrons?

d-orbital Signup and view all the answers

What is the correct filling order of orbitals based on energy levels?

s, p, d Signup and view all the answers

Which of these statements about electron spins is correct?

Electrons in the same orbital must have opposite spin. Signup and view all the answers

Which of the following configurations represents Sodium correctly?

Na = 1s2 2s2 2p6 3s1 Signup and view all the answers

What occurs when electrons are unpaired and unbalanced?

The atom may exhibit a different arrangement. Signup and view all the answers

Which rule states that no single orbital can hold more than two electrons?

Pauli Exclusion Principle Signup and view all the answers

How many energy levels does Sodium have based on its electron configuration?

3 energy levels Signup and view all the answers

Which orbital holds 6 electrons?

p-orbital Signup and view all the answers

What occurs when positive ions hit the negatively charged detection plate?

They gain an electron, producing a flow of charge. Signup and view all the answers

How does the presence of a charged ion affect its path in mass spectrometry?

A 2+ charged ion produces a smaller radius path. Signup and view all the answers

In mass spectrometry analysis, how is the abundance of isotopes measured?

By the current produced in relation to flight times. Signup and view all the answers

What is the ratio of Cl+ ions observed in chlorine mass spectra?

3:1 Signup and view all the answers

How can the mass of chlorine isotopes be formed from Cl2+ ions?

Using varied combinations of two different isotopes. Signup and view all the answers

What is a characteristic feature of electron orbitals?

Different types include s, p, d, and f orbitals. Signup and view all the answers

What is demonstrated by the spectra of chlorine isotopes?

Different ratios indicate relative abundances. Signup and view all the answers

In the calculation of average relative atomic mass (Ar) given the abundances, which of the following is correct?

Ar is determined from the weighted average of isotope masses based on abundance. Signup and view all the answers

What does ionisation energy refer to?

The energy required to remove a single electron from a mole of gaseous atoms. Signup and view all the answers

How do successive ionisation energies typically behave?

They increase in energy required for each successive electron removed. Signup and view all the answers

What happens to the first ionisation energy as you move down a group in the Periodic Table?

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

What does a sudden large increase in ionisation energy indicate?

A change in energy level is occurring. Signup and view all the answers

Why is the first ionisation energy of Aluminium lower than expected?

It possesses a pair of electrons with opposite spin causing repulsion. Signup and view all the answers

What trend is observed for first ionisation energy across a period?

It increases due to decreasing atomic radius. Signup and view all the answers

What is the reason for the increase in ionisation energy when electrons are removed?

The electrostatic attraction between the nucleus and electrons increases. Signup and view all the answers

What factor lessens the effect of electrostatic forces of attraction down a group in the Periodic Table?

Increasing atomic radius. Signup and view all the answers

Study Notes

Fundamental Particles

The model for atomic structure has evolved over time, with the current model consisting of a small, dense, positively charged nucleus surrounded by orbiting electrons in electron shells.
This model was discovered through the Rutherford scattering experiment in 1911.
The nucleus contains protons and neutrons, giving it a positive charge and holding almost all of the atom's mass.
In a neutral atom, the number of protons and electrons is equal.

Determining the Number of Fundamental Particles

Mass Number (A): Represents the sum of protons and neutrons in an atom.
Atomic Number (Z): Represents the number of protons in an atom.
Example: If Atomic Number = 7 and Mass Number = 14, then: Proton number = 7 and Neutron number = 14 - 7 = 7

Relative Atomic Mass and Isotopes

Relative Atomic Mass (Ar): The mean mass of an atom of an element, divided by one twelfth of the mean mass of an atom of the carbon-12 isotope.
Isotopes: Atoms of the same element with the same atomic number, but a different number of neutrons, resulting in a different mass number.
Isotopes react chemically in the same way because their proton number and electron configuration is the same.
However, isotopes have different physical properties due to their differing mass numbers.

Ions and Mass Spectrometry

Ions: Formed when an atom loses or gains electrons, resulting in an overall charge.
Mass Spectrometry: Analytical technique used to identify isotopes and determine the relative atomic mass of an element.
Time of Flight (TOF) Mass Spectrometry: Records the time taken for isotopes to reach a detector, generating spectra displaying each isotope present.
Steps in TOF Mass Spectrometry:
- Ionization: Sample vaporized and injected into a chamber, where high voltage causes electrons to be removed, creating +1 charged ions.
- Acceleration: Positively charged ions accelerated towards a negatively charged detection plate.
- Ion Drift: Ions deflected by a magnetic field into a curved path, with radius depending on charge and mass.
- Detection: Ions hit the detection plate, gain an electron, and produce a flow of charge. The greater the abundance, the greater the current.
- Analysis: Current values and flight times are used to generate a spectra printout showing isotope abundance.

Interpretation of Mass Spectra

A 2+ charged ion will be affected more by the magnetic field, creating a path of smaller radius.
This results in a halved m/z (mass to charge ratio) and is represented by a trace at half the expected m/z value on spectra.

Chlorine Spectra

Mass spectra of chlorine display a characteristic pattern due to the presence of two isotopes:
- Cl+ ions: 3:1 ratio
- Cl2+ ions: 3:6:9 ratio
This ratio arises from the different combinations of chlorine isotopes in the molecule.

Electron Configuration

Electron Orbitals: Electrons are held in clouds of negative charge called orbitals. Different types of orbitals exist: s, p, d, and f, each with a unique shape.
Electron Orbitals and the Periodic Table: These orbitals correspond to blocks on the Periodic Table, with each element in the block's outer electrons residing in that orbital.
Electron Orbital Capacity: Each type of orbital can hold a specific number of electrons:
- s-orbital: 2 electrons
- p-orbital: 6 electrons
- d-orbital: 10 electrons
Orbitals fill in order of increasing energy, from s to d, with each orbital completely filled before the next one is used.
Electron Spin: Within orbitals, electrons pair up with opposite spin to achieve stability. This spin is represented by arrows.

Rules for Electron Configuration

Lowest energy orbitals are filled first.
Electrons with the same spin fill an orbital before pairing begins. 
No single orbital holds more than two electrons.

Exceptions to Electron Configuration Rules

Unpaired Spins: Unpaired electrons with unbalanced spins create instability due to natural electron repulsion.
Electron Rearrangement: Electrons may rearrange to achieve stability, leading to changes in electron configuration.

Ionisation Energy

Definition: Minimum energy required to remove one mole of electrons from one mole of atoms in a gaseous state.
Units: kJmol-1
Successive Ionisation Energies: Ionization energies for removing subsequent electrons, typically requiring more energy due to increased electrostatic attraction between the nucleus and remaining electrons.
Trends in First Ionisation Energy:
- Along a Period: Ionisation energy increases due to decreasing atomic radius and greater electrostatic forces of attraction.
- Down a Group: Ionisation energy decreases due to increasing atomic radius and shielding effects, reducing electrostatic force.
Sudden Large Increase in Successive Ionisation Energies: Indicates a change in energy level as the electron is removed from a closer orbital, requiring more energy.
Supporting Evidence for Atomic Orbital Theory: This large energy increase provides evidence for the atomic orbital theory.
Aluminum Exception: Aluminum's first ionisation energy is lower than expected due to a single pair of electrons with opposite spins, causing repulsion and reducing the energy required to remove the outer electron.

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Description

Explore the fundamental concepts of atomic structure, including mass number, atomic number, and the discovery of the nucleus. This quiz covers key topics such as protons, neutrons, relative atomic mass, and isotopes. Test your understanding of how these particles contribute to the overall structure of atoms.