Structure of Matter

Question 1

What is the smallest indivisible particle of matter originally thought to be?

Answer 1

Atom

Atoms were once considered the smallest units of matter, but they have a substructure.

Question 2

What composes all matter?

Answer 2

Elements

Each element has distinct physical and chemical properties.

Question 3

What is the central core of an atom called?

Answer 3

Nucleus

The nucleus contains most of the atomic mass.

Question 4

What surrounds the nucleus of an atom?

Answer 4

Cloud of electrons

Electrons move in orbits around the nucleus.

Question 5

What is the approximate radius of an atom?

Answer 5

10−10 m

This radius refers to the electronic orbits.

Question 6

What is the approximate radius of a nucleus?

Answer 6

10−15 m

The nucleus is significantly smaller than the atom itself.

Question 7

True or False: Atoms can be divided into smaller components.

Answer 7

True

Atoms have a substructure, allowing them to be divided.

Question 8

Fill in the blank: Each atom consists of a small central core called the _______.

Answer 8

Nucleus

Question 9

What distinguishes each element from others?

Answer 9

Physical and chemical properties

These properties are based on the atom’s structure.

Question 10

What are the two kinds of fundamental particles in the nucleus?

Answer 10

Protons and neutrons.

Question 11

What charge do protons and neutrons have?

Answer 11

Protons are positively charged; neutrons have no charge.

Question 12

In an electrically neutral atom, what is true about the number of protons and electrons?

Answer 12

The number of protons is equal to the number of electrons.

Question 13

What does the formula X(A/Z) represent in relation to an atom?

Answer 13

X is the chemical symbol, A is the mass number, and Z is the atomic number.

Question 14

What are isotopes?

Answer 14

Atoms having nuclei with the same number of protons but different number of neutrons.

Question 15

What are isotones?

Answer 15

Atoms having the same number of neutrons but different number of protons.

Question 16

What are isobars?

Answer 16

Atoms with the same number of nucleons but different number of protons.

Question 17

What are isomers?

Answer 17

Atoms containing the same number of protons and neutrons but differing in their nuclear energy states.

Question 18

Which combination of neutrons and protons generally results in more stable nuclides?

Answer 18

Combinations that have an almost equal number of neutrons and protons.

Question 19

What is the neutron-to-proton ratio for stable nuclei as Z increases beyond about 20?

Answer 19

It becomes greater than 1 and increases with Z.

Question 20

What percentage of stable isotopes have even numbers of protons and neutrons?

Answer 20

More than half.

Question 21

What is the unified atomic mass unit (u) defined as?

Answer 21

1/12 of the mass of a carbon-12 atom.

Question 22

What is the average mass of atoms of an element in a sample called?

Answer 22

Relative atomic mass or atomic weight.

Question 23

What is Avogadro’s number?

Answer 23

6.022 × 10^23 atoms per gram atomic weight (or mole).

Question 24

What is the mass of a proton in atomic mass units (u)?

Answer 24

1.00728 u.

Question 25

What is the mass of a neutron in atomic mass units (u)?

Answer 25

1.00866 u.

Question 26

What is the mass of an electron in atomic mass units (u)?

Answer 26

0.0005486 u.

Question 27

What is the concept of mass defect?

Answer 27

The mass difference when the nucleus is formed, converted into binding energy.

Question 28

What is the basic unit of energy?

Answer 28

Joule (J).

Question 29

What is an electron volt (eV)?

Answer 29

The kinetic energy acquired by an electron in passing through a potential difference of 1 V.

Question 30

What is the relationship between mass (m) and energy (E) according to Einstein's principle?

Answer 30

E = mc^2.

Question 31

What happens to the mass of a particle as its velocity increases?

Answer 31

The mass increases.

Question 32

What is the formula for kinetic energy (Ek)?

Answer 32

Ek = 1/2 mv^2.

Question 33

Fill in the blank: The mass of an electron at rest is sometimes expressed in terms of its _______.

Answer 33

[energy equivalent (E0)].

Question 34

What model proposed by Niels Bohr describes the movement of electrons around the nucleus?

Answer 34

The Bohr model

Question 35

What prevents electrons from leaving the atom according to the Bohr model?

Answer 35

The centripetal force of attraction between the positively charged nucleus and the negatively charged electron

Question 36

According to classical physics, what happens to an accelerating or revolving electron?

Answer 36

It must radiate energy, leading to a continuous decrease of the radius of the orbit

Question 37

What does the discrete change of energy in atoms indicate?

Answer 37

Electrons jump between specific orbits, emitting light of particular frequencies

Question 38

What are the two fundamental postulates of Bohr's theory?

Answer 38

* Electrons exist only in orbits where angular momentum is an integral multiple of h/2π * No energy is gained or lost while in permissible orbits

Question 39

What is the K shell in terms of electron configuration?

Answer 39

The innermost orbit or shell

Question 40

How is the maximum number of electrons in an orbit calculated?

Answer 40

2n², where n is the orbit number

Question 41

What is the maximum number of electrons in the second orbit?

Answer 41

8 electrons

Question 42

What are valence electrons?

Answer 42

Electrons in the outermost orbit

Question 43

What influences the chemical properties of an atom?

Answer 43

The number of electrons in the outermost orbit

Question 44

What is binding energy in the context of electrons?

Answer 44

The potential energy of the electrons in the atom

Question 45

What does the energy level diagram represent?

Answer 45

The energy levels of the orbital electrons

Question 46

What is the relationship between binding energy and atomic number (Z)?

Answer 46

Binding energies are greater for higher Z atoms due to greater nuclear charge

Question 47

What happens when energy is imparted to a valence electron?

Answer 47

It can create a state of atomic instability and emit energy as optical radiation

Question 48

What are the four different forces in nature, ranked by strength?

Answer 48

* Strong nuclear force * Electromagnetic force * Weak nuclear force * Gravitational force

Question 49

What is the role of the strong nuclear force?

Answer 49

It holds the nucleons together in the nucleus

Question 50

What is the range of the strong nuclear force?

Answer 50

Short-range, effective within ~10−15 m

Question 51

What is a potential well in the context of nucleons?

Answer 51

A region of strong attraction experienced by nucleons close to the nucleus

Question 52

What is the significance of the mass defect in nuclear binding?

Answer 52

It provides the energy required to keep the nucleons together

Question 53

What happens to an α particle approaching a nucleus?

Answer 53

It encounters a potential barrier due to Coulomb repulsion

Question 54

What is the shell model of the nucleus?

Answer 54

It assumes nucleons are arranged in shells representing discrete energy states

Question 55

What occurs when a nucleus returns to a lower energy state?

Answer 55

It emits energy equal to the energy difference of the two states

Question 56

What is a β− particle?

Answer 56

A particle emitted during the nuclear transformation of a neutron into a proton

Question 57

What is the outcome of the β-decay process?

Answer 57

A neutron disintegrates into a proton, an electron, and a neutrino

Question 58

What are elementary particles?

Answer 58

Particles that are not known to have a substructure.

Question 59

What theory classifies all known elementary particles?

Answer 59

The Standard Model of particle physics.

Question 60

What are the two classes of particles?

Answer 60

* Fermions * Bosons

Question 61

What characterizes fermions?

Answer 61

Spin in odd half-integer quantum units of angular momentum.

Question 62

What characterizes bosons?

Answer 62

Spin of an integer number.

Question 63

What are the two kinds of fundamental particles of matter?

Answer 63

* Quarks * Leptons

Question 64

List the six types of quarks.

Answer 64

* Up (u) * Down (d) * Charm (c) * Strange (s) * Top (t) * Bottom (b)

Question 65

List the six types of leptons.

Answer 65

* Electron (e) * Electron neutrino (νe) * Muon (μ) * Muon neutrino (νμ) * Tau (τ) * Tau neutrino (ντ)

Question 66

What principle states that for every particle of matter there is a corresponding particle of antimatter?

Answer 66

The principle discovered by Paul Dirac.

Question 67

What are the building blocks of hadrons?

Answer 67

Quarks.

Question 68

What are gluons?

Answer 68

Field particles that hold quarks together.

Question 69

What are messenger particles?

Answer 69

Particles that carry force in a force field.

Question 70

How many messenger particles mediate the four forces of nature?

Answer 70

13 messenger particles.

Question 71

List the messenger particles for electromagnetism.

Answer 71

* Photon (γ)

Question 72

List the messenger particles for the strong force.

Answer 72

* Eight gluons

Question 73

List the messenger particles for the weak force.

Answer 73

* W+ * W− * Z0

Question 74

What is the graviton?

Answer 74

Theoretical messenger particle for gravity (not yet detected).

Question 75

True or False: Matter particles can attain the speed of light.

Answer 75

False.

Question 76

What happens to the mass of ultrahigh-energy particles in accelerators?

Answer 76

They have greater mass but do not attain the speed of light.

Question 77

What is the Higgs boson?

Answer 77

A particle that is believed to give mass to other particles.

Question 78

What is the role of the Higgs field?

Answer 78

It generates the rest mass of matter.

Question 79

When was the Higgs boson tentatively observed?

Answer 79

July 2012.

Question 80

What is the relationship between wavelength, frequency, and velocity of electromagnetic waves?

Answer 80

c = νλ.

Question 81

What is Planck's constant?

Answer 81

6.626 × 10−34 J-s.

Question 82

How is the energy of a photon calculated?

Answer 82

E = hν.

Question 83

What is the atomic structure of an atom?

Answer 83

A positively charged nucleus surrounded by a cloud of negatively charged electrons.

Question 84

What is the radius of an atom approximately?

Answer 84

~10−10 m.

Question 85

What is the atomic number (Z)?

Answer 85

The number of protons in an atom.

Question 86

What are isotopes?

Answer 86

Atoms with the same Z but different numbers of neutrons.

Question 87

What are isobars?

Answer 87

Atoms with the same A but different Z.

Question 88

What is nuclear stability influenced by?

Answer 88

The combination of neutrons (n) and protons (p) in the nucleus.

Question 89

What is the mass-energy equivalence formula?

Answer 89

E = mc².

Question 90

What is the energy equivalent of an electron at rest?

Answer 90

0.511 MeV.

Question 91

What is the maximum number of electrons in any orbit given by?

Answer 91

2n², where n is the orbit number.

Question 92

What defines the binding energy of electrons in various orbits?

Answer 92

The magnitude of the Coulomb force of attraction.

Question 93

What is the relationship between atomic mass and unified atomic mass units?

Answer 93

Atomic mass may be expressed in unified atomic mass units, u.

Question 94

What is the relationship between wavelength and energy of a photon?

Answer 94

As the wavelength becomes shorter, the energy of the photon becomes greater.