Electron Theory Flashcards
With regards to Protons Neutrons and Electrons, what are the individual charges?
Protons
Protons are positively charged particles in the nucleus.
Neutrons
Neutrons are neutral particles in the nucleus.
Electrons
Electrons are negatively charged particles travelling in various orbits (shells) around the atomic nucleus. They are attracted to the positively charged protons, which prevents the electrons from moving away from the nucleus.
What particles make up the mass of an atom?
Protons and neutrons make up the mass of an atom; electrons have almost no mass.
An atom with a positive or negative electrical charge is said to be?
Positively or negatively charged atoms are called ions. A charged atom is said to be ionised.
What is a molecule?
A molecule is an electrically neutral group of two or more atoms held together by chemical bonds. A charged molecule is also called an ion.
What is a compound?
In a pure compound, each molecule contains the same number of atoms of each element. It follows therefore that elements can only combine to form compounds in certain fixed proportions.
What can cause outer electrons to detach from the nucleus?
Sources of such energy may be heat, light, electrostatic fields, etc.
What is a positive Ion?
Positive Ion: The electron once detached from the atom is able to move around the structure of the material and is called a “Free Electron”. The atom which has lost the electron has now gained an overall positive charge and is therefore called a “Positive Ion”.
What is a negative Ion?
Negative Ion: When an atom gains an electron in its outer orbit it becomes overall negatively charged and is called a “Negative Ion”
Generally what makes a good conductor?
Good conductors contain atoms having less than four electrons in the outer shell (valence orbit).
Examples of good conductors?
Copper, aluminium, and silver.
When are semi-conductors best at conducting?
Semiconductors are better conductors at higher temperatures, unlike metals which are poorer conductors at higher temperatures.
Compared to metals, semi-conductors have ?
Semiconductors have a small number of free electrons compared to metals. If we assume that metals, on average, have one free electron per atom, then semiconductors might have one free electron per million atoms, at room temperature.
Generally, semi-conductors have how many electrons in the outer shell?
4
Examples of semi-conductors?
Silicon and germanium.
With regards to Electrons in the outer shell, Good insulators are said too?
Good insulators contain atoms having more than four electrons in their outer shell (valence orbit).
