Before the 20th century, the term matter included ordinary matter composed of atoms and excluded other energy phenomena such as light or sound. This concept of matter may be generalized from atoms to include any objects having mass even when at rest, but this is ill-defined because an object's mass can arise from its (possibly massless) constituents' motion and interaction energies. Thus, matter does not have a universal definition, nor is it a fundamental concept in physics today. Matter is also used loosely as a general term for the substance that makes up all observable physical objects. 

All the objects from everyday life that we can bump into, touch or squeeze are composed of atoms. This atomic matter is in turn made up of interacting subatomic particles—usually a nucleus of protons and neutrons, and a cloud of orbiting electrons. Typically, science considers these composite particles matter because they have both rest mass and volume. By contrast, massless particles, such as photons, are not considered matter, because they have neither rest mass nor volume. However, not all particles with rest mass have a classical volume, since fundamental particles such as quarks and leptons (sometimes equated with matter) are considered "point particles" with no effective size or volume. Nevertheless, quarks and leptons together make up "ordinary matter", and their interactions contribute to the effective volume of the composite particles that make up ordinary matter. QUESTIONS:

Q1:
1. What was included in the term matter prior to the 20th century?
2. What was a part of the idea of matter before the 20th century?
3. In the years before the 20th century, what was the term matter comprised of?
Q2:
1. What was excluded from the term matter prior to the 20th century?
2. What wa nots a part of the idea of matter before the 20th century?
3. In the years before the 20th century, what was the term matter not comprised of?
Q3:
1. What does science consider photons?
2. How do scientists classify photons?
3. What do scientists believe photons to be?
Q4:
1. What is one massless particle?
2. What is an example of a particle without mass?
3. Give an example of a massless particle.
Q5:
1. Are photons matter?
2. Do photons count as matter?
3. Are photons considered to be matter?
Q6:
1. Give an example of a fundamental particle.
2. What is one thing that is considered a fundamental particle?
3. What could be given as an example of a fundamental particle?
Q7:
1. Give an example of a fundamental particle, besides leptons.
2. What is one thing that is considered a fundamental particle other than leptons?
3. What could be given as an example of a fundamental particle in addition to leptons?
Q8:
1. What are quarks and leptons considered?
2. What classification is given to quarks and leptons?
3. What do scientists consider leptons and quarks to be?
Q9:
1. What is loosely meant by the term matter?
2. What is an approximative definition of the term matter?
3. What does the term matter mean more or less?
Q10:
1. What effective size do point particles have?
2. State the effective size of point particles.
3. How large is the effective size of a point particle?
