Atoms and subatomic Particles

what is an atom

An atom is the basic unit of matter, consisting of a nucleus made of protons and neutrons, surrounded by electrons. It is the smallest particle of an element that retains the chemical properties of that element. Atoms combine to form molecules, which make up all substances in the universe.

Atoms are the _________

building blocks of matter

Atoms are the _____ particles of an ______ that still have the elements properties

smallest, element

An atom is the _________ into which an element can be divided without losing its ________.

smallest particle, chemical properties

The word “Atom” comes from the Greek atomos and means _____

indivisible

Who was Democritus and what was his theory?

Democritus was a Greek philosopher who theorized that matter is made up of tiny, indivisible particles called atoms.

What did Democritus reason would happen if a stone were continually cut into smaller and smaller pieces?

He reasoned that eventually, there would be a piece so small it could no longer be divided.

Who proposed the atomic theory in 1804?

John Dalton proposed the atomic theory in 1804.

What did Dalton's theory state about matter?

Dalton's theory stated that all matter is composed of extremely small particles called atoms.

According to Dalton, what are atoms of a given element like?

Atoms of a given element are identical in size, mass, and other properties. This has been proven false

What did Dalton's theory say about the divisibility of atoms?

Dalton's theory stated that atoms cannot be subdivided, created, or destroyed. This has been proven false

What does Dalton's theory say about how atoms of different elements combine?

Atoms of different elements can combine in simple whole-number ratios to form chemical compounds.

According to Dalton, what happens during chemical reactions?

In chemical reactions, atoms are combined, separated, or rearranged.

How has Dalton's atomic theory been modified over time?

Dalton's atomic theory has been largely accepted, but with three changes: atoms can be subdivided, not all atoms of an element are identical in mass, and atoms can be created or destroyed in nuclear reactions.

What is true about the mass of atoms of a given element?

Not all atoms of a given element are identical in mass (due to isotopes).

Can atoms be created or destroyed?

Using nuclear fission and fusion techniques, atoms can be created or destroyed by changing them into other atoms.

Who discovered the first subatomic particle?

J.J. Thomson

What did J.J. Thomson realize about the accepted model of the atom?

It did not account for negatively or positively charged particles.

What particle did J.J. Thomson discover in 1897?

The electron, a negatively charged particle

What model of the atom did J.J. Thomson propose?

The plum pudding model.

What did J.J. Thomson's model fail to recognize?

It failed to recognize the positive charges in the atom as particles

What experiment did Rutherford conduct?

The Gold Foil Experiment

What did Rutherford expect to happen when particles were fired at the gold foil?

He expected them to go straight through the foil

What actually happened when particles were fired at the gold foil in Rutherford’s gold foil experiment?

Most went straight through, but some bounced back.

What did Rutherford's experiment reveal about the structure of an atom?

Atoms have a dense, positive central core called the nucleus.

What did Rutherford discover about the space inside the atom?

Atoms are mostly empty space

In Rutherford’s Gold Foil Experiment, what was the expected outcome versus the actual result?"

The expected result was that all particles would go straight through the foil, but in reality, some particles bounced back, indicating a dense, positive nucleus at the center of the atom.

What is Bohr’s model of the atom also called?

The planetary model.

What did Bohr propose about the location of electrons in an atom?

Electrons are in orbitals around the positively charged nucleus.

State the model that first included electrons as subatomic particles. 

1. J.J.Thomson

State one conclusion about the internal structure of the atom that resulted  from the gold foil experiment.

Atoms have a dense, positive central core=nucleus

State one way in which the Bohr model agrees with the Thomson model.

Agrees about the  presence of electrons.

Subatomic particles are particles that are _____ than the atom.

Smaller

____, ____, and _____ are the three main subatomic particles found in an atom. 

Protons, neutrons, and electrons

What are the three main Subatomic particles found in an atom?

Protons, neutrons, and electrons