What are the four elements that were thought to make up all matter?
- Fire
- Water
- Air
- Earth
This idea was prevalent in ancient philosophy and science.
Who is John Dalton and what is he known for?
An English school teacher and scientist who revisited the idea of atoms
Dalton lived from 1766 to 1844 and contributed significantly to atomic theory.
What is the Scanning Tunneling Microscope and when was it invented?
A high-powered microscope invented in 1981 that enables scientists to see individual atoms
This invention marked a significant advancement in the field of microscopy.
What did Thomson discover about cathode ray tubes?
He discovered that if most of the air was removed from the tube and electricity was passed through, it produced cathode rays
Thomson’s work contributed to the understanding of electrons.
What is an electron?
A particle with one negative charge
Electrons are fundamental components of atoms.
True or false: John Dalton believed that empty space exists.
FALSE
Dalton did not believe in the existence of empty space in his atomic theory.
Who was Ernest Rutherford?
A student of Thomson’s who studied atomic structure
Rutherford’s work led to significant advancements in understanding the atom.
What is the Alpha Particle experiment?
An experiment conducted by Rutherford to study atomic structure
It provided evidence for the existence of the atomic nucleus.
Define nucleus in the context of an atom.
A small area in the center of the atom
What is a proton?
An atomic particle that has a positive charge
Protons are found in the nucleus of an atom.
What is a neutron?
An atomic particle that exists in the nucleus of an atom
Neutrons have no charge and contribute to the atomic mass.
Who was Niels Bohr?
A scientist who studied hydrogen atoms because they contain only one electron
Bohr’s model of the atom introduced the concept of electron orbits.
What is an electron cloud?
An area around an atomic nucleus where an electron is likely to be located
This concept reflects the probabilistic nature of electron positions.
What are quarks?
Smaller particles that make up protons and neutrons
There are six types of quarks, which combine to form protons and neutrons.
What is the composition of protons?
- 2 up quarks
- 1 down quark
Protons are made of quarks held together by the strong force.
What is the composition of neutrons?
- 1 up quark
- 2 down quarks
Neutrons are also made of quarks and contribute to the atomic mass.
What are isotopes?
Atoms of the same element that have different numbers of neutrons
Isotopes have the same atomic number but different atomic masses.
What is a mass number
A mass number represents the total number of protons and neutrons in an atom’s nucleus.
Who is Henri Becquerel and what did he study?
A scientist who studied minerals containing uranium
Henri Becquerel (1852-1908) conducted significant research in radioactivity.
Define Radioactive elements.
Elements that spontaneously emit radiation
The term was named by Marie Curie (1867-1934).
What is Nuclear Decay?
A process where an unstable atomic nucleus changes into a more stable nucleus by emitting radiation
This process can involve alpha, beta, or gamma decay.
What is an Alpha Particle?
A particle made of two protons and two neutrons
The emission of an alpha particle decreases the atomic number by 2.
What occurs during Beta decay?
An atom changes into another by releasing a high-energy electron
A new proton is formed in the process.
What is a Gamma Particle?
A form of electromagnetic radiation
Gamma decay increases the atomic number by 1, changing elements into different elements.
