Atomic Structure and Bonding

Question 1

What is an atom?

Answer 1

An atom is the smallest unit of an element that retains the chemical properties of that element. It consists of a nucleus (protons and neutrons) and electrons orbiting around the nucleus.

Question 2

What is a molecule?

Answer 2

A molecule is a group of atoms bonded together, representing the smallest fundamental unit of a chemical compound that can take part in a chemical reaction.

Question 2

What was John Dalton’s contribution to atomic theory?

Answer 2

John Dalton proposed that all matter is made up of atoms, which are indivisible particles. He also introduced the concept that atoms combine in fixed ratios to form compounds.

Question 3

What is an ion?

Answer 3

An ion is an atom or molecule that has gained or lost one or more electrons, resulting in a net electric charge.

Question 4

What was J.J. Thomson’s contribution to atomic structure?

Answer 4

J.J. Thomson discovered the electron and proposed the plum pudding model of the atom, where electrons are embedded in a positively charged sphere.

Question 4

What did Robert Millikan discover?

Answer 4

Robert Millikan conducted the oil drop experiment and determined the charge of an electron.

Question 5

What did Henry Moseley contribute to atomic theory?

Answer 5

Henry Moseley discovered that the atomic number, rather than atomic mass, defines the identity of an element, leading to the modern periodic table arrangement.

Question 6

What was Ernest Rutherford’s key discovery?

Answer 6

Ernest Rutherford discovered the atomic nucleus through his gold foil experiment, revealing that atoms have a dense, positively charged nucleus.

Question 7

What is Niels Bohr known for in atomic theory?

Answer 7

Niels Bohr developed the Bohr model of the atom, which introduced quantized orbits for electrons and explained the emission spectra of elements.

Question 8

What is the atomic number of an element?

Answer 8

The atomic number is the number of protons in the nucleus of an atom, which determines the element’s identity.

Question 9

What is the mass number of an atom?

Answer 9

The mass number is the sum of protons and neutrons in the nucleus of an atom.

Question 10

How do you find the number of neutrons in an atom?

Answer 10

The number of neutrons is found by subtracting the atomic number from the mass number: Neutrons = Mass Number - Atomic Number.

Question 11

What are isotopes?

Answer 11

Isotopes are different forms of the same element that have the same number of protons but different numbers of neutrons.

Question 12

Provide an example of isotopes and their mass numbers.

Answer 12

Carbon-12 and Carbon-14 are isotopes of carbon. Carbon-12 has 6 protons and 6 neutrons, while Carbon-14 has 6 protons and 8 neutrons.

Question 13

What is the electron configuration for Oxygen (atomic number 8)?

Answer 13

The electron configuration for Oxygen is 1s² 2s² 2p⁴.

Question 14

How is the electron configuration of an atom determined?

Answer 14

The electron configuration is determined by the arrangement of electrons in atomic orbitals according to the Aufbau principle, Hund’s rule, and the Pauli exclusion principle.

Question 15

What is the electron configuration for Argon (atomic number 18)?

Answer 15

The electron configuration for Argon is 1s² 2s² 2p⁶ 3s² 3p⁶.

Question 15

Describe the shape of s orbitals.

Answer 15

S orbitals are spherical in shape.

Question 16

Describe the shape of p orbitals.

Answer 16

P orbitals have a dumbbell shape and are oriented along the x, y, and z axes.

Question 17

What are the main groups on the periodic table?

Answer 17

The main groups include alkali metals, alkaline earth metals, transition metals, halogens, and noble gases.

Question 18

How does electron affinity vary across periods and down groups?

Answer 18

Electron affinity generally increases across periods (left to right) and decreases down groups (top to bottom).

Question 18

How does ionization energy vary across periods and down groups?

Answer 18

Ionization energy generally increases across periods (left to right) and decreases down groups (top to bottom).

Question 19

How does electronegativity vary across periods and down groups?

Answer 19

Electronegativity generally increases across periods (left to right) and decreases down groups (top to bottom).

Question 20

How does ionic radius change across periods and down groups?

Answer 20

Ionic radius decreases across periods (left to right) and increases down groups (top to bottom).

Question 21

What is electrovalency (ionic bonding)?

Answer 21

Electrovalency involves the transfer of electrons from one atom to another, forming positively and negatively charged ions that attract each other.

Question 22

What is metallic bonding?

Answer 22

Metallic bonding involves a “sea of electrons” that are free to move around, creating a lattice of metal cations held together by these delocalized electrons.

Question 22

What is covalency (covalent bonding)?

Answer 22

Covalency involves the sharing of electron pairs between atoms to form a stable molecule.

Question 23

What is a hydrogen bond?

Answer 23

A hydrogen bond is a weak attraction between a hydrogen atom covalently bonded to an electronegative atom and another electronegative atom.

Question 24

What is a coordinate bond (dative covalent bond)?

Answer 24

A coordinate bond is a type of covalent bond where both electrons in the bond come from the same atom.

Question 25

Provide examples of complexes with coordinate bonds.

Answer 25

Examples include [Fe(CN)₆]³⁻, [Fe(CN)₆]⁴⁻, [Cu(NH₃)₄]²⁺, and [Ag(NH₃)₂]⁺.

Question 26

What is the shape of a linear molecule?

Answer 26

Linear molecules have a straight-line shape, with bond angles of 180°, e.g., CO₂.

Question 27

What are Van der Waals forces?

Answer 27

Van der Waals forces are weak, temporary forces of attraction between molecules due to transient dipoles.

Question 28

What is the shape of a non-linear (bent) molecule?

Answer 28

Non-linear (bent) molecules have an angle less than 180°, e.g., H₂O.

Question 29

What are the types of radioactive decay?

Answer 29

The types of radioactive decay are alpha decay, beta decay, and gamma decay.

Question 29

What is the shape of a tetrahedral molecule?

Answer 29

Tetrahedral molecules have four bonds arranged around a central atom with bond angles of approximately 109.5°, e.g., CH₄.

Question 30

What is the shape of a pyramidal molecule?

Answer 30

Pyramidal molecules have a central atom with three bonds and a lone pair, creating a pyramidal shape with bond angles of around 107°, e.g., NH₃.

Question 31

What are the properties of alpha particles?

Answer 31

Alpha particles are positively charged, have low penetration power, and can be stopped by a sheet of paper.

Question 31

What are the properties of gamma rays?

Answer 31

Gamma rays have no charge, high penetration power, and can only

Question 32

What are the properties of beta particles?

Answer 32

Beta particles are negatively charged, have moderate penetration power, and can be stopped by a sheet of plastic or glass.

Question 33

How is the half-life of a radioactive material defined?

Answer 33

The half-life is the time required for half of the radioactive atoms in a sample to decay.

Question 34

How do you calculate the remaining quantity of a radioactive substance after a given number of half-lives?

Answer 34

Remainingquantity = Initialquantity × (1/2) ^𝑛 where 𝑛 is the number of half-lives.

Question 35

What is the difference between natural and artificial radioactivity?

Answer 35

Natural radioactivity occurs spontaneously in nature, while artificial radioactivity is induced by human activities, such as nuclear reactions.

Question 36

What are some applications of radioactivity?

Answer 36

Applications include medical imaging (e.g., PET scans), radiation therapy for cancer treatment, radiocarbon dating, and industrial applications such as tracer studies.

Question 37

How do you balance a simple nuclear equation?

Answer 37

Ensure that the sum of atomic numbers and mass numbers is equal on both sides of the equation.