3.1 electron theory Flashcards
What are the main subatomic particles and their electric charges?
Protons are positively charged, neutrons are neutral, and electrons are negatively charged.
What is the structure of an atom?
An atom consists of protons and neutrons in the nucleus, with electrons orbiting around it.
What is the charge of a single electron?
The charge of a single electron is negative.
What is the charge of a single proton?
The charge of a single proton is positive.
What is the elementary charge?
The elementary charge is the magnitude of the charge of a proton or electron, denoted by the symbol e.
What makes an atom electrically neutral?
An atom is electrically neutral if it has an equal number of protons and electrons.
What is a negatively charged atom called?
A negatively charged atom is called a negative ion.
What is a positively charged atom called?
A positively charged atom is called a positive ion.
What defines a molecule?
A molecule is an electrically neutral group of two or more atoms held together by chemical bonds.
What is an example of a molecule of an element?
The molecule of the element oxygen is made up of two oxygen atoms (O2).
What is an example of a compound?
Sodium chloride (NaCl) is an example of an ionic compound made up of sodium and chlorine.
How are positive ions formed?
Positive ions are formed when an atom loses an electron.
How are negative ions formed?
Negative ions are formed when an atom gains an electron.
What are the two main types of compounds covered in this module?
The two main types of compounds are molecules held together by covalent bonds and ionic compounds held together by ionic bonds.
What is the molecular structure of conductors?
In a conductor, such as metals, atoms are closely packed in a crystal lattice, allowing electrons in the outer shells to move freely. This high electron mobility makes metals good conductors of electricity and heat.
What are examples of good conductors?
Examples of strongly conductive metals include copper, aluminium, and silver.
What defines a semiconductor?
A semiconductor is a material whose conductivity is between that of a good conductor and a good insulator. Its conductivity can be affected by temperature, doping, or light.
How does temperature affect semiconductors?
Semiconductors are better conductors at higher temperatures, unlike metals which are poorer conductors at higher temperatures.
What is the typical number of free electrons in semiconductors?
Semiconductors have a small number of free electrons compared to metals, typically one free electron per million atoms at room temperature.
What is the atomic structure of semiconductors?
Semiconductors generally contain atoms with four electrons in their outer shell (valence orbit).
What are examples of semiconductors?
Examples of semiconductors include silicon and germanium.
What is the structure of insulators?
In insulators, electrons are tightly connected to atoms or molecules, preventing them from breaking away and resulting in no free electrons for conduction.
What defines good insulators?
Good insulators contain atoms having more than four electrons in their outer shell (valence orbit).
What are examples of good insulators?
Examples of good insulators include mica and porcelain.
