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.
