chemistry notes

chapter 7

What did Thales believe the world was formed from?

Water.

What did Anaximenes propose everything is made of?

Air.

What concept did Democritus introduce regarding particles?

The indivisible particle called an atom.

What are the four fundamental elements introduced by Aristotle?

Earth, water, air, and fire.

What does the law of conservation of mass state?

Matter cannot be created or destroyed in a chemical reaction.

What was one of John Dalton's main propositions about atoms?

All matter is made of atoms, which are identical for a given element.

What incorrect claim did John Dalton make regarding atoms?

That atoms are indivisible.

Who discovered the first subatomic particles and identified electrons?

J.J. Thompson.

What theory did J.J. Thompson propose regarding atomic structure?

The plum pudding theory.

What did Rutherford discover through the gold foil experiment?

The nucleus of the atom.

What new particle did James Chadwick discover?

The neutron.

What are isotopes?

Atoms of an element that have different numbers of neutrons.

What kinds of radiation did Ernest Rutherford discover?

Alpha particles, beta particles, and gamma rays.