chemistry test prep chapter 4--THE ATOM

Who was the first scientist to coin the word atom?

Democritus

Who is Democritus and how did he contribute to the history of the atom?

Democritus proposed his ideas about the atom: matter is actually composed of tiny, indivisible, and indestructible parts

Did the Greed world believe Democritus? Why or why not? Who did they believe?

No, they did not believe Democritus because he had no proof. They believe Aristotle instead because he was more popular at the time.

Who created the first atomic theory?

Dalton

What is the major components of Dalton's atomic theory?

Matter is composed of extremely small particles called atoms

Atoms are indivisible and indestructible

All atoms of the same element are identical in size, mass and chemical properties.

Atoms of one element are different from atoms of another element

Different atoms combine in simple whole-number ratios to form compounds.

In a chemical reaction, atoms are separated, combined or rearranged

What is the conversation of mass?

Mass of reactants = mass of products

Basically what you start with is what you end with

What is a reactant?

What you start with in a chemical reaction

What is a product?

What you end with in a chemical reaction

What are the three subatomic particles that make up an atom?

Protons, Neutrons, and Electrons

What is an electron?

Negatively charged particles, orbit around the nucleus, have almost no mass.

What is a proton?

Positively charged particles in an atoms nucleus, gives an element its identity, has a mass amount of 1. IT NEVER EVER EVER CHANGES

What is a neutron?

Subatomic particles with no charge but with a mass nearly equal to that of a proton, which is 1. It is located inside the nucleus.

Who discovered the electron?

JJ Thomson

How was the electron discovered?

JJ Thomson completed the cathode ray experiment. Saw that the cathode had a stream of negatively charged particles by using charged plates to bend the stream. The ray avoided the negative plate. Concluded there must be a negative particle. Called it the electron.

What was the name and describe the picture of the model created by JJ Thomson?

"Plum pudding" Looks like a chocolate chip cookie, positive cookie with negative charges throughout.

The main things I need to know about JJ Thomson.

Discovered the electron--negative charged particle

Did this with the cathode Ray tube experiment

Model he created was the "plum pudding" AKA chocolate chip cookied

Who is Rutherford?

He is a scientist who tested the theory atomic structure. He set up the gold foil experiment that lead him to find a new atomic model. he discovered the nucleus and the proton.

Describe the gold foil experiment

Rutherford aimed a beam of positive alpha particles and gold foil and observed what happened. Some particles went straight through the others were deflected (bounced off). Concluded the presence of a nucleus and a positively charged particle--the proton

The main things I need to know about Rutherford

Discovered the proton with a positive charge and the nucleus

Create the Gold Foil

Model--nucleus in the middle with protons and electrons moving around outside the nucleus

Who discovered the neutron?

Chadwich

How did neutron get discovered?

By MATH. He discovered that the nucleus had more weight than just protons.

What is inside the nucleus of an atom?

Protons and Neutrons

What is outside the nucleus of an atom?

Electrons

What is the mass of a proton?

1

What is the mass of an electron?

0

What is the mass of a neutron?

1

What is the charge of a proton?

positive (+)

What is the charge of an electron?

negative (-)

What is the charge of a neutron?

neutral (N) NO CHARGE

What is the idea that Bohr came up with involving the atom?

In 1913, Bohr comes up with the idea that atomic structure has to do with the electron arrangement in atoms and their chemical properties.

What is Bohr's Atomic Theory

Thought the electron traveled around the nucleus like the planets traveled around the sun--CALLED AN ORBIT

Bohr called each orbit an energy level--electrons can move between the energy levels

What is ground state?

Where the electron should be

What is excited state?

Where the electron moves to when it gains more energy

What is the atomic number? What is a good way to remember it on the periodic table?

the number of protons in an atom. It never changes and it is the smaller number on the periodic table

What is the mass number?

The number of protons and number of neutrons

In a neutral atom what is the same?

The number of protons and electrons.

What is an ion?

A charged atom. it is positively charged when there is more protons than electrons. It is negatively charged when there is more electrons than protons. An ion forms when an atom either gains or loses electrons. REMEMBER THE PROTONS IN AN ATOM NEVER EVER EVER CHANGES

What is an isotope?

An atom with the same number of protons, but different number of neutrons as another form of the element. It is the same element but in a different form due to a different number of neutrons.

What does C-13 mean?

It is a way to write an isotope. It is carbon and the mass is 13. Which means it has 6 protons (remember it never changes) and 7 neutrons.

How do you know an element is an ion?

There is a + or - with a number on the upper right of the element. If the element says 2+, it means the atom is positively charged and there is 2 less electrons than protons. If it says 2-, it means it is negatively charged and there are two more electrons in the atom.

What is the average atomic mass?

average mass of an element's isotopes.

The isotope with the greatest percent abundance helps to dictate the mass of that element.

In the periodic table, what is a group?

Vertical column--up and down--Memory trick. GroUP has the word UP in it. It will remind you the direction--up and down

In the periodic table, what is a period?

Horizontal row--side to side