Chapter 1-4 Chem Definitions

Question 1

Cathode rays

Answer 1

Streams of negatively charge electrons that travel in straight lines from the cathode to anode and are deflected by magnetic and chemical fields and have sufficient energy to move small objects like a paddle wheel

Question 2

Energy level

Answer 2

Fixed energy values that an electron in an atom may have

Question 3

Ground state

Answer 3

Of an atom is the one in which electrons occupy the lowest available energy levels

Question 4

Excited state

Answer 4

Of an atom is the one in which the electrons occupy higher energy levels than those available in the ground state

Question 5

Heisenberg’s Uncertainty Principle

Answer 5

It is impossible to measure at the same time both the velocity and position of an electron

Question 6

An orbital

Answer 6

A region of space around the nucleus with a high probability of finding an electron

Question 7

Dalton’s Atomic Theory

Answer 7

All matter is made up of small particles called atoms

These atoms are indivisible

Question 8

Sub level

Answer 8

A subdivision of a main energy level and consists of one or more orbitals of the same energy

Question 9

Element

Answer 9

A substance that cannot be split into simpler substances by chemical means

Question 10

Triad

Answer 10

A group of three elements with similar properties where the atomic weight of the middle element is approximately the average of the other two

Question 11

Newlands’ Octaves

Answer 11

Arrangements of elements where the first and the eight element counting from a particular element have similar properties

Question 12

Mendeleev’s Periodic Law

Answer 12

When elements are arranged in order of increasing relative atomic mass the properties of the elements recur periodically

Question 13

Modern periodic law

Answer 13

When element are arranged in order of increasing atomic number, the properties of the elements recur periodically

Question 14

Mass number

Answer 14

The sum of the number of protons and neutrons in the nucleus of an atom of an element

Question 15

Isotopes

Answer 15

Atoms of the same element which have different mass numbers due to the different number of neutrons in the nucleus

Question 16

Relative atomic mass

Answer 16

The average of the mass numbers of the isotopes of the element, as the occurring naturally, taking the abundances into account and expressed on a scale in which the atoms of the carbon 12 isotope have a mass of exactly 12 units

Question 17

The modern periodic table

Answer 17

Is an arrangement of elements in order of increasing atomic number

Question 18

Atomic number

Answer 18

PROTONS ONLY

Question 19

The principle of mass spectrometry

Answer 19

Charged particles moving in a magnetic field are deflected to different extents according to their masses and are thus separated according to these masses

Question 20

Electron configuration

Answer 20

The arrangement of electrons in an atom of an element

Question 21

Aufbau Principle

Answer 21

When building up the electron configuration of an atom in its ground state, the electrons occupy the lowest available energy levels

Question 22

Hund’s rule of maximum multiplicity

Answer 22

When two or more orbitals of equal energy are available, the electrons occupy them singly before filling them in pairs

Question 23

Pauli Exclusion Principle

Answer 23

No more than two electrons may occupy and orbital and they must have opposite spin