Science Unit 2

A neutron has an electric charge of _ and a mass of _ .

0 and 1

The element boron has two naturally occurring isotopes. The most common isotope of boron has 5 protons and 6 neutrons in the nucleus. Which of the following combinations could represent the other naturally occurring isotope of boron?

5 protons and 5 neutrons

Rutherford's new model of the atom contained 2 key components. The first was that the center of the atom contained

A dense, solid core called the nucleus, that had positive charge

What happens if you change the number of electrons

An ion of the element

The smallest particle of an element that has all of the chemical properties of that element is a(n)

Atom

The number of protons in the nucleus of an atom of an element is also known as the ____________ of that element

Atomic number

Which of the following statements describes a part of the atomic theory that has been modified in the 200 years since Dalton proposed it?

Atoms are the smallest unit of matter and can't be subdivided

According to Dalton's atomic theory, atoms cannot

Be destroyed

Robert Millikan

Calculated the charge of an electron from Oil drop experiment

Since Dalton proposed the atomic theory, scientists have discovered that atoms of a given element

Can have different masses

John Dalton

Compounds whole number ratio and spostulates AND explained the law of conservation of mass, definite proportions and multiple proportions

Which of the people we discussed was a Natural Scientist that believed atoms are the smallest particle of matter?

Dalton

was the fist to perform experiments to prove the existence of atoms.

Dalton

Which TWO of the following people envisioned the atom in the same way

Dalton and Democritus

Daltons Atomic Theory

Dalton provided experimental evidence for the atom (and molecules), and crafted four postulates that formed the basis of his theory

Dalton's idea that all matter is composed of atoms was first introduced in ancient Greece by the philosopher named.

Democritus

Which of the people we studied was a Natural Philosopher that believed atoms were the smallest particle of matter?

Democritus

coined the word "Atomos"

Democritus

Joseph Black

Discovered that air isn't a element

The fact that a cathode ray was deflected by a magnetic field was evidence that the particles making up the ray had

Electrical charge

JJ Thompson experimented with cathode ray tubes and eventually discovered the Corpuscle, or the

Electron

JJ Thompson

Experimented with cathode ray tubes, discovered electron and negative charge and plum pudding model

Thompson

His model of the atom placed electrons in a "sea of positive charge" like plum pudding

Where do electrons stay?

In first outer ring

What happens if you change the number of neutrons

It doesn't change the element

Question 3 After realizing how the cathode ray behaved around a magnet and electric plate, Thomson deduced that the cathode ray was really a particle that had mass and a

Negative charge

Thomson knew that electrons had ____________ because they were deflected away from an object with a negative charge and attracted to a positive charge

Negative charge

Ernest Rutherford

Performed gold foil experiment, discovered nucleus, and showed atom is mostly empty space

Antoine Lavoisier

Proposed that mass is conserved in chemical reactions (can't be created or destroyed)

Empodocles

Proposed the 4 elements of matter earth, fire, water, air

The particles that account for most of the mass in an atom are

Protons and neutrons

The particles that make up the nuclei of atoms are

Protons and neutrons

An atom's identity is determined by the total number of

Protons in the nucleus of the atom

Discovered the nucleus

Rutherford

used the Gold Foil Experiment

Rutherford

Ernest Rutherford's gold-foil experiments showed that atoms have a nucleus that is

Small and positively charged

The mass number of an atom of an element is the

Sum of the protons and neutrons in the nucleus of the atom

What happens if you change the number of protons in a element?

The element changes

The ____________ of two isotopes of an element are always different.

The mass number

In Rutherford's Gold foil experiment, what did MOST of the alpha particles do when fired at the thin piece of gold?

They passed right through the atoms

Where do protons stay in a atom?

They stay in the nucleus

Formulated the Plum Pudding Model

Thompson

discovered the electron

Thompson

Rutherford's new atomic model contained 2 key components. The second, and radical idea, was that most of the atom

Was made up of empty space

By experimenting with cathode ray tubes and electric plates, Thomson was able to determine that the cathode ray

Was repelled by negative charge

Democritus

said everything in the universe was made up of tiny particles called atoms.