Chemistry - Unit 4

anion

A negative ion, which gains electrons, is called an ___________________. Nonmetals are this form of ions.

cation

A positive ion, which loses electrons, is called a ______________. Metals are this form of ions.

gold foil

Also in the early 1900s, during his famous ______________ ____________ experiment, Ernest Rutherford bombarded a sheet of gold foil with a beam of positively charged particles called alpha particles.

isotopes

Also known as nuclides. These are atoms of the same element that have different masses because they have different numbers of neutrons. They are atoms of the same element because they have the same number of protons, which is what identifies an element.

electron

An English scientist, Sir William Crookes discovered the ___________________.

rutherford

Another physicist, Ernest ________________, who was a student of Thomson's, disputed the Plum Pudding model.

john dalton

Because of the proposed atomic theory, _______________ _______________ is known as "The Father of the Atomic Theory."

energy levels

Bohr believed that the electrons were located in distinct areas outside of the nucleus which he called ________________ _________________.

accepted

Dalton's theory was ____________________ by the scientific community, but over time parts of his theory are questioned.

empty space

Democritus believed that matter was made up of atoms and ___________ ____________.

atom

Democritus is the first to use the term _____________ from the Greek word atomos meaning indivisible.

0

Electrons have a mass of about ___________ amu.

plum-pudding

Eventually, J.J. Thomson proposed a new atomic model, the _____________-_________________ model, in which electrons are evenly distributed throughout a sphere of positive charge in such a way that the atom is electrically neutral.

neutral

In a ________________ atom, the number of electrons = the number of protons.

oil-drop

In the early 1900s, an American Physicist, Robert Millikan, determined the electron's actual charge using his famous ____________-______________ experiment.

electron

In the late 1800s, the English Physicist, J. J. Thomson, determined a very large charge to mass ratio of an ___________________.

1803

In what year was the Atomic Theory published?

electrons protons

Ions form through the loss or gain of _________________. The number of _____________ never changes.

periodic table

Molar mass is found on the ________________ _______________ and varies slightly from one to the next.

atomic theory

More than 2000 years after Democritus, an English scientist and school teacher, John Dalton, proposed an ________________ _______________ of his own and published a series of papers in the early 1800s.

bohr

Niels Bohr, a Danish physicist, developed the ____________ Model of the atom.

attract repel

Opposite charges _________________ and like charges ______________.

quarks

Over the past few decades, physicists have discovered new particles which they have called "___________________". These have been found to be the fundamental building blocks of protons and neutrons. In more recent years, these have been split into even smaller subatomic particles.

subdivided

Part of Dalton's Atomic Theory: Atoms cannot be ___________________, created or destroyed. (not really true)

whole number

Part of Dalton's Atomic Theory: Atoms of different elements combine in simple _______________ _______________ ratios to form compounds.

same different

Part of Dalton's Atomic Theory: Atoms of the _______________ element are identical, and atoms of __________________ elements are different.

chemical

Part of Dalton's Atomic Theory: In __________________ reactions, atoms are combined, separated or rearranged.

atoms

Part of Dalton's Atomic Theory: all matter is made of ______________.

nucleus

Protons and neutrons are found packed tightly in the _________________ of the atom, while the electrons are found traveling in the space outside of the _______________.

1

Protons and neutrons have a mass of about _________ amu.

nucleus

Rutherford thought that there was going to be some deflection because the positive alpha particles would hit the positive space in the atom. However, there was very little deflection, and he realized that the alpha particles that bounced back toward the source had hit the ______________________.

discoveries

Since Dalton's time, many more ____________________ about the atom have been made as the result of the dedicated endeavors of scientists who made atomic research their life's work.

proton

The ________________ was discovered by German physicist Eugin Goldstein.

neutron

The __________________was eventually discovered by the English Physicist, Sir James Chadwick.

molar mass

The amount of a substance (in grams) that contains Avogadro's Number of particles. g/mol

number of protons

The atomic number is the same as the __________________ ______ __________________.

alpha particles

The gold foil experiment used _____________ __________________, which are two protons, from the radioactive source polonium.

average atomic mass

The mass number is never found on the periodic table. The mass on the periodic table is the _________________ ________________ ___________ that includes the masses of all naturally occurring isotopes of that particular element.

cloud

The modern day atomic model is the ____________ model. Described the position of the electrons as a cloud and you can only account probability of the positions of the electrons. Created by Schrödinger.

mass number

The number of protons + the number of neutrons equals the _________________ __________________.

true

True or false: Dalton's atomic theory begins to break down at atoms cannot be subdivided,created or destroyed, and atoms of the same element are identical.

false

True/False: Avogadro's number is only used with atoms.

atomic mass unit

What does "amu" stand for?

universal mass unit

What does "u" stand for?

a solid sphere

What does Dalton's picture of an atom look like?

gold foil experiment

What experiment concluded that the atom was mostly empty space and that there was a small, dense, positively charged nucleus in the middle of the atom.

cathode ray tube

What instrument was used to discover the electron?

mole

What is the SI Unit for measuring the amount of a substance?

avogadro's number

What is the number of particles in a mole that is defined as the amount of a substance that contains as many particles as there are atoms in exactly 12 g of carbon-12? 6.02 x 10²³

nuclear symbol

What is this called?

hyphen notation

What is this notation called?: element name or symbol - mass number

the nucleus is too large

What is wrong with Rutherford"s model of the atom? (in terms of the nucleus)

law of definite proportions

What law is this?: A chemical compound always contains the same elements in exactly the same proportions by mass.

law of multiple proportions

What law is this?: If two elements form more than one compound between them (ex. CO and CO2), then, the ratios of the masses of the second element which combine with a fixed mass of the first element will be ratios of small whole numbers.

law of conservation of mass

What law is this?: Mass cannot be created or destroyed in ordinary chemical or physical changes.

aristotle

Which Greek philosopher thought that matter is it continuous and infinitely divisible?

democritus

Which Greek philosopher thought that matter is it divisible only until a basic, indivisible particle that cannot be divided any further is reached?

Thomson

Who used the cathode ray tube to help discover the electron?

ions

____________ are charged atoms with an unequal number of electrons and protons in a given atom.