Chapter 11 Science

Democritus

A Greek philosopher that said everything in the world is made up of tiny particles called atomos or atoms (indivisible)

Bohr's Theory vs. Current atomic theory

Bohr believed that electrons traveled on certain pathways with the ability to jump from one to another. The current atomic theory says that we have the electron cloud where electrons are likely to be found.

Identify the atomic Models of Dalton, Thomson, Rutherford, Bohr, and Current.

Both Democritus and Dalton used the solid sphere model which is just a sphere. Thomson used the plum-pudding or chocolate chip ice cream model. Rutherford used a model with the nucleus as a dot in the center and electrons throughout. Bhor made the planetary model and the current model is similar to Bohr's but uses the electron cloud.

Einstein

Brilliant German physicist who made the theory of relativity and helped make the modern atomic theory.

Max Planck

German physicist who made the discovery of energy quanta. Helped form the modern atomic theory.

Forces in an atom

Gravitational, Electromagnetic, Strong, & Weak Forces

Werner Heisenberg

Heisenberg said that it is impossible to determine both exact position and speed of the electron as they move around the atom.

What would happen to a nucleus containing two or more protons if strong force was absent?

If the strong force was absent the nucleus would fall art and the atom would become unstable and fall apart.

How are ion created?

Ions are created when an atom either looses or gains an atom.

Discuss the Development of the atomic theory

It began with Democritus who said that everything was made up of atoms and they are indivisible. His model was the solid sphere. Then Dalton comes up with his theory after performing his experiments. He said that everything is made up of atoms and can't be created, divided, or destroyed. He also said that all atoms are the same and other atoms are different, also he said that atoms can combine to form new substances. Dalton also uses the solid sphere model. After that came Thompson who used the Cathode Ray found a negatively charged particles now called an electron. He used the plum-pudding model. Soon came Ruther with his gold-foil experiment. He found the a small positive charged nucleus in the atoms. His model almost looked like a chocolate chip cookie. After this came Bhor who said that electrons travel on pathways and can jump from one pathway to another. He used the planetary model. Finally came the modern atomic theory which now has the idea of the electron cloud.

What happens to radioactive atoms over time?

Over time the radioactive nucleus begins to fall apart and change over time when falling apart it begins to give off particles and energy.

John Dalton

Quaker scientist and teacher who performed experiments to form his atomic theory. He said everything is made up of atoms - atoms can't be created, divided, or destroyed - atoms of an element are exactly alike and atoms of other elements are different - atoms can be joined with other atoms to form new substances.

Rutherford's Gold Foil Experiment

Rutherford shot a stream of alpha particles (using radium and lead) towards a gold-foil target. As expected most particles passed right through but some were slightly deflected and few even bounced straight back.

Difference between atomic mass and atomic number

The atomic number is the number of protons in the atom but the atomic mass is the weighted average of the natural isotope of the element.

Cathode-Ray experiment

The experiment JJ Thomson used to find electrons. He shot a beam produced by electricity towards a charged plate. The beam was attracted to the positive plate which shows that the atoms have a negative particle in them.

Rutherford

Used a gold foil experiment to discover that most of the mass in the atom is located in the center. He named this group of mass the nucleus of the atom.

Enrico Fermi

Was an Italian physicist and the creator of the world's first nuclear reactor. Helped to form the modern atomic theory.

ion

a charged particle - you loose an electron=positive ion - you gain an electron=negative ion.

neutron

a neutral charge or no charged particle in the nucleus. The mass is 1 amu

electron cloud

a region around the nucleus of an atom where electrons are likely to be found.

nucleus

an atom's central region, which is made up of protons and neutrons.

Isotopes

atoms that have the same number of protons but a different number of neutrons - they always have the same number of protons but can have a different number of neutrons which means they can have different masses.

Gravitational Force

depends on the mass of the object and the distance between them. - gravitational force does not really affect atoms.

JJ Thomson

discovered there are particles in the atoms called electrons. He discovered this by using the Cathode-Ray experiment. JJ Thompson then discovered the plum-pudding or chocolate chip ice cream model.

Bohr

electrons orbit the nucleus at fixed energies and distances able to jump from one level to another but not to exist in the space between.

weak force

important in radioactive atoms - allows a neutron to change into a proton and electron.

strong force

keeps the protons in the nucleus - since the protons and neutrons are so close the strong force is needed to keep them together.

Electromagnetic force

like charges repel & unlike charges attract - this force keeps the electrons around the nucleus (protons)

How to calculate atomic mass

multiply the percent and mass number and then add them up to get atomic mass

electron

negatively charged particle outside the nucleus in the electron cloud. The mass is about 0 amu

mass number

number of protons and neutrons in the nucleus of an atom.

proton

positive charged particle in the nucleus. The mass is 1 amu

Atom

smallest unit of an element that maintains the properties if an element.

atomic number

the number of protons in the nucleus.

Atomic Mass Unit (AMU)

the unit used to measure the mass of a particle inside the atom

atomic mass

weighted average of the natural isotopes of the element. To find it you multiple the percent and the mass number and then add them up to get atomic mass.