Physics-19 The nuclear atom and Radioactivity PreQuiz

_____ is when a particle (atom or molecule) becomes electrically charged by losing or gaining electrons

• Ionisation

• Plum Pudding Model

• alpha particle

• Nucleus

• neutron

Answer explanation

Ionization (or ionisation) is the process by which an atom or a molecule acquires a negative or positive charge by gaining or losing electrons, often in conjunction with other chemical changes. The resulting electrically charged atom or molecule is called an ion. Ionization can result from the loss of an electron after collisions with subatomic particles, collisions with other atoms, molecules and ions, or through the interaction with electromagnetic radiation. Heterolytic bond cleavage and heterolytic substitution reactions can result in the formation of ion pairs. Ionization can occur through radioactive decay by the internal conversion process, in which an excited nucleus transfers its energy to one of the inner-shell electrons causing it to be ejected.

J.J Thomsons model of an atom, in which he thought electrons were randomly distributed within a positively charged cloud is the _______.

• Ionisation

• Plum Pudding Model

• alpha particle

• Nucleus

• neutron

Answer explanation

The plum pudding model is one of several historical scientific models of the atom. First proposed by J. J. Thomson in 1904^[1] soon after the discovery of the electron, but before the discovery of the atomic nucleus, the model tried to explain two properties of atoms then known: that electrons are negatively charged particles and that atoms have no net electric charge. The plum pudding model has electrons surrounded by a volume of positive charge, like negatively charged "plums" embedded in a positively charged "pudding".

An ______ is a cluster of 2 protons and 2 neutrons emitted from a nucleus in one type of radioactivity

• Ionisation

• Plum Pudding Model

• alpha particle

• Nucleus

• neutron

Answer explanation

1. An Alpha particle is a helium nucleus emitted by some radioactive substances, originally regarded as a ray.

The _____ is the small, positively charged center of the atom.

• Ionisation

• Plum Pudding Model

• alpha particle

• Nucleus

• neutron

Answer explanation

The atomic nucleus is the small, dense region consisting of protons and neutrons at the center of an atom, discovered in 1911 by Ernest Rutherford based on the 1909 Geiger–Marsden gold foil experiment. After the discovery of the neutron in 1932, models for a nucleus composed of protons and neutrons were quickly developed by Dmitri Ivanenko and Werner Heisenberg. An atom is composed of a positively charged nucleus, with a cloud of negatively charged electrons surrounding it, bound together by electrostatic force. Almost all of the mass of an atom is located in the nucleus, with a very small contribution from the electron cloud. Protons and neutrons are bound together to form a nucleus by the nuclear force.

A _____ is a subatomic particle that has no charge and that is found in the nucleus of an atom

• Ionisation

• Plum Pudding Model

• alpha particle

• Nucleus

• neutron

Answer explanation

1. A neutron is a subatomic particle of about the same mass as a proton but without an electric charge, present in all atomic nuclei except those of ordinary hydrogen.

The ______ is the electric charge of a subatomic particle compared to the charge on a proton.

• relative charge

• relative mass

• isotope

• radioactive substance

• radioactive decay

Answer explanation

So the relative charge of a particle is defined as the charge of that particle divided by the charge of a proton. In other words, we're measuring the charge of that particle relative to the charge of a proton. And that's why it's called relative charge.

_____ is the mass of a subatomic particle compared to the mass of a proton.

• relative charge

• relative mass

• isotope

• radioactive substance

• radioactive decay

Answer explanation

Relative atomic mass (symbol: A_r; sometimes abbreviated RAM or r.a.m.), also known by the deprecated synonym atomic weight, is a dimensionless physical quantity defined as the ratio of the average mass of atoms of a chemical element in a given sample to the atomic mass constant. The atomic mass constant (symbol: m_u) is defined as being 1/12 of the mass of a carbon-12 atom. Since both quantities in the ratio are masses, the resulting value is dimensionless.

Atoms of the same element that have different numbers of neutrons are called:

• relative charge

• relative mass

• isotope

• radioactive substance

• radioactive decay

Answer explanation

An isotope is - each of two or more forms of the same element that contain equal numbers of protons but different numbers of neutrons in their nuclei, and hence differ in relative atomic mass but not in chemical properties; in particular, a radioactive form of an element.

A _____ is a substance that spontaneously gives out radiation from the nuclei of its atoms.

• relative charge

• relative mass

• isotope

• radioactive substance

• radioactive decay

Answer explanation

Radionuclides (or radioactive materials) are a class of chemicals where the nucleus of the atom is unstable. They achieve stability through changes in the nucleus (spontaneous fission, emission of alpha particles, or conversion of neutrons to protons or the reverse).

_______ is a spontaneous process in which unstable nuclei lose energy by emitting radiation

• relative charge

• relative mass

• isotope

• radioactive substance

• radioactive decay

Answer explanation

Radioactive decay (also known as nuclear decay, radioactivity, radioactive disintegration, or nuclear disintegration) is the process by which an unstable atomic nucleus loses energy by radiation. A material containing unstable nuclei is considered radioactive. Three of the most common types of decay are alpha, beta, and gamma decay, all of which involve emitting particles. The weak force is the mechanism that is responsible for beta decay, while the other two are governed by the electromagnetism and nuclear force.