Topic 1: Atomic Structure and the Periodic Table for A-Level Chemistry (Edexcel)

Which subatomic particle has a relative charge of +1 and is found in the nucleus of an atom?

Proton

Protons determine the atomic number of an element.

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Which subatomic particle has no charge but contributes to the mass of the nucleus?

Neutron

Neutrons add mass and help stabilise the nucleus.

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Which subatomic particle has a relative charge of −1 and occupies orbitals around the nucleus?

Electron

Electrons exist in orbitals arranged in energy levels around the nucleus.

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What is the small, dense central region of an atom that contains protons and neutrons called?

Nucleus

The nucleus contains nearly all the mass of the atom.

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True or False:

Most of the mass of an atom comes from electrons.

False

Almost all atomic mass comes from protons and neutrons in the nucleus.

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Fill in the blank:

Protons and neutrons have a relative mass of approximately _______ compared with each other.

Their masses are roughly equal on the relative scale used in chemistry.

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Fill in the blank:

The relative mass of an electron compared with a proton is approximately _______.

1/2000

This is why electrons contribute very little to atomic mass.

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Which particle determines the chemical behaviour of an element because of its arrangement around the nucleus?

Electron

Chemical reactions involve the rearrangement of electrons.

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True or False:

Protons, neutrons and electrons all have the same relative charge.

False

Their charges are +1, 0 and −1 respectively.

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What is the basic structure consisting of a nucleus surrounded by electrons?

Atom

Atoms are the fundamental building blocks of elements.

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What does the atomic (proton) number of an element represent?

Number of protons

The atomic number (Z) identifies the element.

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What does the mass number of an atom represent?

Total number of protons and neutrons

Mass number (A) counts nucleons in the nucleus.

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Fill in the blanks:

Mass number (A) is the sum of the number of _______ and _______.

protons; neutrons

Electrons are not included because their mass is negligible.

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Atoms of the same element that have different numbers of neutrons are known as what?

Isotopes

Isotopes have the same atomic number but different mass numbers.

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Why do isotopes of an element have the same chemical properties?

Same electron arrangement

Chemical behaviour depends on electrons, not neutrons.

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True or False:

Isotopes of an element have identical mass numbers.

False

Isotopes differ in the number of neutrons, so their mass numbers differ.

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Which technique is used to measure isotopic masses and relative abundances with high accuracy?

Mass spectrometry

A mass spectrometer separates ions based on mass-to-charge ratio.

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In a time of flight mass spectrometer, what process first converts atoms or molecules into ions?

Ionisation

Electrons are removed to form positive ions.

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What is the traditional method of ionisation used in a TOF mass spectrometer for small molecules and atoms?

Electron gun

This involves bombarding gaseous samples with a beam of high - energy electrons fired from the gun

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During electrospray ionisation what is the sample dissolved in?

A polar, volatile solvent, such as water or methanol.

The solvent can act as a source of protons to facilitate the ionisation process M + H⁺ → MH⁺ where M represents a large molecule

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During electrospray ionisation, what occurs after the sample is dissolved?

The solution is pumped through a hypodermic needle, forming a fine mist of droplets with a +1 charge.

This process is considered a soft technique as generally no fragmentation occurs.

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After ionisation in a TOF mass spectrometer, what causes acceleration of the ions so they all have the same kinetic energy?

An electric field

The same kinetic energy is required to separate the ions, because if two ions have the same KE the heavier one will travel slower.

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What property of isotopes can be determined from the peak heights in a mass spectrum?

Relative abundance

Taller peaks indicate more abundant isotopes.

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What stage of a TOF mass spectrometer allows ions to separate according to their mass-to-charge ratio?

Ion drift

Due to having the same kinetic energy, lighter ions travel faster and reach the detector sooner.

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What stage of a **mass spectrometer** records the **arrival of ions** and produces a signal?

Ion detection ## Footnote The signal is proportional to ion abundance.

What property of **isotopes** can be determined from the **peak heights in a mass spectrum**?

Relative abundance ## Footnote Taller peaks indicate more abundant isotopes.

What occurs at the **ion detector** to measure the number of **ions** present in a **mass spectrometer**?

* Ions hit the detector. * Each ion gains an electron producing a current. * The **size of the current is relative to abundance.** ## Footnote The current can then be used to measure the relative abundance

What quantity can be calculated from **isotopic masses** and their **abundances**?

Relative atomic mass ## Footnote Calculated using a weighted mean of isotopic masses.

# Fill in the blanks: The **average mass of atoms of an element** accounting for **isotopic abundance** is called the _\_\_\_\_\_\_ _\_\_\_\_\_\_ _\_\_\_\_\_\_.

Relative atomic mass ## Footnote This value appears on the Periodic Table.

# True or False: **Mass spectrometry** can be used to determine the **relative molecular mass** of a substance.

True ## Footnote The molecular ion peak gives information about molecular mass.

What type of **ion** is typically formed when molecules are **ionised without fragmentation** in a mass spectrometer?

Molecular ion ## Footnote Represented as M⁺.

Why do **lighter ions** reach the detector faster than **heavier ions** in a **TOF mass spectrometer**?

Higher velocity ## Footnote All ions have the same kinetic energy, so lighter ions move faster.

When calculating **relative atomic mass** from **isotopic abundance**, what type of **mean** is used?

Weighted mean ## Footnote Each isotopic mass is multiplied by its relative abundance.

What is **electron configuration**?

The arrangement of **electrons** around the nucleus in energy levels, sub-shells, and orbitals. ## Footnote Describes how electrons are distributed in shells and sub-shells..

What type of **sub-shell** contains a **maximum of two electrons**?

s sub-shell ## Footnote An s sub-shell contains one orbital.

Which type of **sub-shell** contains **three orbitals** and can hold **up to six electrons**?

p sub-shell ## Footnote Each orbital holds two electrons.

Which type of **sub-shell** contains **five orbitals** and can hold **up to ten electrons**?

d sub-shell ## Footnote d sub-shells first appear in the third shell.

# Fill in the blank: A single **orbital** can hold a maximum of _\_\_\_\_\_\_ electrons.

2 ## Footnote The electrons must have opposite spins.

What is the **energy required** to remove one electron from each atom in **one mole of gaseous atoms** called?

First ionisation energy ## Footnote Symbolised as IE₁.

In what **state** must atoms be when defining **ionisation energy**?

Gaseous ## Footnote Ensures interactions between atoms do not affect the energy value.

What is the **general equation** for the **first ionisation energy of sodium**?

Na(g) → Na⁺(g) + e⁻ ## Footnote Shows removal of one electron from a gaseous atom.

What is the **general equation** for the **second ionisation energy of sodium**?

Na⁺(g) → Na2⁺(g) + e⁻

What does a **large jump** between **successive ionisation energies** indicate?

Electron removed from a new inner shell. ## Footnote Inner shells are more strongly attracted to the nucleus so much more energy is needed

# True or False: **Successive ionisation energies** always **increase**.

True ## Footnote Each electron is removed from a more positively charged ion.

What does the **pattern of ionisation energies across Period 3** provide evidence for?

sub-shell structure ## Footnote Small drops occur when electrons enter higher-energy p orbitals.

What feature in **ionisation energy data** indicates **electrons occupying paired orbitals**?

A small drop in ionisation energy between two successive values. ## Footnote Electron repulsion makes removal easier.

# Fill in the blank: Across **Period 3**, the **first ionisation energy** generally _\_\_\_\_\_\_ from Na to Ar.

increases ## Footnote Nuclear charge increases while shielding is similar.

Why does **ionisation energy** decrease down **Group 2** from Be to Ba?

Increased distance and shielding reduce attraction to the nucleus. ## Footnote Outer electrons are further from the nucleus and less strongly attracted.

# True or False: **Ionisation energy** increases down a group because **atoms get larger**.

False ## Footnote Increased distance and shielding reduce nuclear attraction.

What evidence do **successive ionisation energies** give about **electron arrangement in atoms**?

Shell structure ## Footnote Large jumps show when electrons begin to be removed from a lower shell.

What determines an element’s **position in the Periodic Table**?

Proton number ## Footnote The number of protons defines the element and its position.

How are elements classified into **blocks** in the Periodic Table?

By highest energy sub-shell ## Footnote The block corresponds to the type of sub-shell being filled by the outer electrons.

# Fill in the blank: Elements in the _\_\_\_\_\_\_ block have their outer electrons entering an **s sub-shell**.

s ## Footnote Groups 1 and 2 are typical examples of s-block elements.

# True or False: The **p block** occupies the **right-hand side** of the Periodic Table.

True ## Footnote It includes Groups 13–18 where electrons fill p orbitals.

Which **block** contains the **transition metals**?

d block ## Footnote These elements have electrons filling the d sub-shell.

# True or False: The **f block** contains the **lanthanides and actinides**.

True ## Footnote These elements involve filling of the f sub-shell.

# Fill in the blank: The **block of an element** depends on which type of _\_\_-\_\_\_\_ is being filled by electrons.

sub-shell ## Footnote Sub-shells include s, p, d and f orbitals.

What **block** do **Group 1 elements** belong to?

s block ## Footnote Their outer electron occupies an s orbital.

# True or False: Elements in the **same block** must have the **same number of electrons**.

False ## Footnote They share the same type of sub-shell being filled, not the same number of electrons.

What type of **sub-shell** is being filled in **p-block elements**?

p sub-shell ## Footnote These sub-shells contain three orbitals.

What general **trend** is observed in **atomic radius across Period 3** from Na to Ar?

Decreases ## Footnote Increasing nuclear charge pulls electrons closer while shielding remains similar.

What happens to **first ionisation energy** across **Period 3** from Na to Ar?

Increases ## Footnote Stronger nuclear attraction makes electrons harder to remove.

# Fill in the blank: Across **Period 3**, atomic radius decreases because nuclear _\_\_\_\_\_\_ increases.

charge ## Footnote More protons attract the same outer shell of electrons more strongly.

# True or False: **Shielding** increases significantly across **Period 3**.

False ## Footnote Electrons are added to the same shell, so shielding changes little.

Why does **atomic radius decrease** across **Period 3**?

Greater nuclear attraction ## Footnote More protons pull the electron cloud closer to the nucleus.

# True or False: The **first ionisation energy** is the energy required to remove **one electron from each atom in one mole of gaseous atoms**.

True ## Footnote This definition applies to the first ionisation energy.

# Fill in the blank: A **higher nuclear charge** leads to a _\_\_\_\_\_\_ first ionisation energy.

higher ## Footnote Electrons are held more strongly by the nucleus.

What type of **structure** explains the **high melting points** of sodium, magnesium and aluminium?

Metallic lattice ## Footnote Strong metallic bonding requires significant energy to break.

# True or False: **Silicon** has a very **high melting point** because it forms a giant covalent structure.

True ## Footnote Strong covalent bonds extend throughout the lattice.

Why do **melting points** drop sharply from **silicon to phosphorus**?

Molecular structure ## Footnote Silicon is macromolecular whereas P₄ molecules are held together by weak intermolecular forces.

# Fill in the blank: **Phosphorus, sulfur and chlorine** have relatively **low melting points** due to _\_\_\_\_\_\_ intermolecular forces.

weak ## Footnote These substances consist of simple molecular structures.

Why does **sulfur** have a **higher melting point than phosphorus**?

Larger molecules ## Footnote S₈ molecules experience stronger London forces than P₄ molecules.

Topic 1: Atomic Structure and the Periodic Table Flashcards

Explain atomic structure and periodic trends by applying models of the atom and electronic configuration. (72 cards)