Chemistry - Atom

Front 1

Define the term isotope of an element.

Back 1

Atoms of an element that have the same number of protons and the same number of electrons but different numbers of neutrons.

Front 2

Define terms: protons, neutrons and electrons.

Back 2

An ELECTRON is a subatomic particle that possesses a negative electrical charge. It is the smallest, in terms of mass, of the three types of subatomic particles. A PROTON is a subatomic particle that possesses a positive electrical charge. A NEUTRON is a subatomic particle that has no charge associated with it; that is, it is neutral

Front 3

Define the terms mass number, atomic number.

Back 3

Atomic number (Z) is equal to the number of protons in nucleus, so it' rqual to the number of electrons. Mass number (A) is equal to the number of protons and neutrons in the nucleus of atom

Front 4

Calculate the number of protons, neutrons and electrons in atoms and ions from the mass number, atomic number and charge.

Back 4

Number of neutrons = mass number - atomic number = A - Z

Front 5

Compare the properties of the isotopes of an element.

Back 5

Isotopes of an element have the same chemical properties(same number of electrons), but their physical properties are often slightly different.

Front 6

Discuss the uses of radioisotopes (4)

Back 6

In nuclear medicine, radioisotopes are used for diagnosis, treatment, and research. Radioactive chemical tracers emitting gamma rays or positrons can provide diagnostic information about a person's internal anatomy and the functioning of specific organs; In food preservation, radiation is used to stop the sprouting of root crops after harvesting, to kill parasites and pests, and to control the ripening of stored fruit and vegetables; In industry, and in mining, radionuclides examine welds, to detect leaks; can serve as tracers

Front 7

State the position of protons, neutrons and electrons in the atom

Back 7

All protons and all neutrons present are found at the center of an atom in a nucleus. The outer (extranuclear) region of an atom contains all of the electrons

Front 8

The Three Isotopes of Hydrogen

Back 8

Protium, Deuterium, and Tritium

Front 9

atomic mass

Back 9

the calculated average mass for the isotopes of an element, expressed on a scale where 126C serves as the reference point.

Front 10

electron shell

Back 10

Region of space about a nucleus that contains electrons that have approximately the same energy and that spend most of their time approximately the same distance from the nucleus. Electron energy increases as the distance of the electron shell from the nucleus increases. An electron in shell 1 has the minimum amount of energy that an electron can have.

Front 11

electron subshell

Back 11

a region of space within an electron shell that contains electrons that have the same energy (because all orbitals within a subshell have the same energy).

Front 12

electron orbital

Back 12

a region of space within an electron subshell where an electron with a specifi c energy is most likely to be found.

Front 13

Three rules for assigning electrons to various shells, subshells, and orbitals.

Back 13

1. Electron subshells are fi lled in order of increasing energy. 2. Electrons occupy the orbitals of a subshell such that each orbital acquires one electron before any orbital acquires a second electron. All electrons in such singly occupied orbitals must have the same spin. 3. No more than two electrons may exist in a given orbital — and then only if they have opposite spins

Front 14

electron configuration

Back 14

a statement of how many electrons an atom has in each of its electron subshells

Front 15

Radioactivity

Back 15

release of energy and matter that results from changes in the nucleus of an atom

Front 16

radioisotopes

Back 16

Radioactive isotopes; an additional neutron or two may upset the binding energy and cause the atom to become unstable. In an unstable atom, the nucleus changes by giving off a neutron to get back to a balanced state. As the unstable nucleus changes, it gives off radiation and is said to be radioactive.