Chemistry: Subatomic Particles and History of the Atom

Comprehensive review flashcards covering subatomic particles (protons, neutrons, electrons), atomic properties, and the historical evolution of the atomic model from Dalton to Bohr.

Based on the provided atomic diagram, what three subatomic particles are labeled?

Electron, Proton, and Neutron.

According to the notes, what is the relative mass of a proton?

A proton has a mass of $1$.

What is the electrical charge of a proton?

The charge of a proton is $+1$.

According to the notes, what is the mass of a neutron?

A neutron has a mass of $1$.

What is the electrical charge of a neutron?

The charge of a neutron is $0$.

What is the relative mass of an electron according to the notes?

An electron has a mass of $0.0005$.

What is the electrical charge of an electron?

The charge of an electron is $-1$.

Where do protons and neutrons exist within an atom?

They exist in a dense core at the centre of the atom (the nucleus).

What is the name of the dense core located at the centre of an atom?

The nucleus.

Where are electrons located according to the subatomic particles section of the notes?

Electrons spread out around the edge of the atom.

Why do the atoms of an element have no overall electrical charge?

Because they contain equal numbers of protons and electrons.

How does the number of protons compare to the number of electrons in an uncharged atom?

The number of protons is equal to the number of electrons ($\text{protons} = \text{electrons}$).

What does the atomic mass of an element represent?

The number of protons and neutrons in the nucleus.

Which element is cited as an example in the notes when discussing atomic mass?

Potassium.

What does the atomic number of an element represent?

The number of protons in the nucleus.

Which subatomic particle's quantity is unique or particular to each element?

Protons (each element has a particular amount of protons).

What relationship exists between protons and electrons in an atom according to the notes?

$\text{protons} = \text{electrons}$ in the atom.

Which scientist proposed an atomic model in $1803$?

John Dalton.

In what year did John Dalton propose his atomic model?

In $1803$.

How did John Dalton describe atoms in his $1803$ atomic model?

He described atoms as solid spheres.

According to John Dalton, what are different spheres made up of?

Different spheres are made up of different elements.

Which scientist concluded in $1897$ that atoms were not solid spheres?

JJ Thomas.

In what year did JJ Thomas conclude that atoms were not solid spheres?

In $1897$.

What did JJ Thomas's measurements reveal regarding subatomic particles?

His measurements showed smaller negatively charged particles known as electrons.

What was the name of the new atomic theory proposed by JJ Thomas?

The "plum pudding model".

How did the plum pudding model describe the structure of the atom?

It showed that the atom was a ball of positive charge with negatively charged particles stuck in it known as electrons.

In the plum pudding model, what particles are stuck inside the ball of positive charge?

Negatively charged particles known as electrons.

What type of electrical charge constitutes the main ball of the plum pudding model?

A positive charge.

Which scientist carried out the alpha particle scattering experiment in $1909$?

Ernest Rutherford.

In what year did Ernest Rutherford perform the alpha particle scattering experiment?

In $1909$.

What was the name of the experiment conducted by Ernest Rutherford in $1909$?

The alpha particle scattering experiment.

What type of particles were fired in Ernest Rutherford's scattering experiment?

Positively charged particles (alpha particles).

Through what material did Rutherford fire positively charged particles?

A thin sheet of gold.

How thick was the gold target used in Rutherford's scattering experiment?

It was a thin sheet of gold.

Based on the plum pudding model, what was expected to happen to the positively charged particles fired at gold?

They were expected to pass through or be deflected slightly.

What happened to most of the positively charged particles in Rutherford's experiment?

Most of the particles went through the thin sheet of gold.

What unexpected behavior was observed for some of the particles in Rutherford's experiment?

Some were deflected more than expected.

What happened to a small number of the particles fired at the gold sheet?

A small number were deflected backwards.

What did the backward deflection of a small number of alpha particles demonstrate about the plum pudding model?

It meant the plum pudding model was wrong.

What is the name of the atomic model proposed by Ernest Rutherford?

The nuclear model of an atom.

How does Rutherford's nuclear model describe the nucleus at the centre of the atom?

As a tiny positively charged nucleus at the centre where most of the mass is concentrated.

Where is most of the mass concentrated according to Rutherford's nuclear model?

In the tiny positively charged nucleus at the centre of the atom.

What surrounds the nucleus in Rutherford's nuclear model of an atom?

A cloud of negatively charged electrons.

According to Rutherford's nuclear model, what makes up most of the volume of an atom?

Most of the atom is empty space.

Which scientist is listed in the notes immediately following Ernest Rutherford?

Niels Bohr.

Which two subatomic particles share the same relative mass of $1$?

Protons and neutrons.

Which subatomic particle has a mass of $0.0005$?

The electron.

Which subatomic particle has an electrical charge of $+1$?

The proton.

Which subatomic particle has an electrical charge of $-1$?

The electron.

Which subatomic particle has an electrical charge of $0$?

The neutron.

How does the mass of a proton compare to the mass of a neutron?

They have the same mass, each having a relative mass of $1$.

How does the mass of an electron compare to the mass of a proton in the notes?

An electron has a mass of $0.0005$, which is much smaller than a proton's mass of $1$.

How does the mass of an electron compare to the mass of a neutron in the notes?

An electron has a mass of $0.0005$, which is much smaller than a neutron's mass of $1$.

How do the electrical charges of a proton and an electron compare?

A proton has a charge of $+1$ and an electron has an equal and opposite charge of $-1$.

Which two subatomic particles are located within the dense core of the atom?

Protons and neutrons.

Where are the negatively charged subatomic particles located relative to the nucleus in Rutherford's model?

In a cloud surrounding the nucleus.

What is the net electrical charge of the nucleus based on its constituents?

It is positively charged because it contains positively charged protons and uncharged neutrons.

What does the atomic mass of potassium measure according to the text?

The number of protons and neutrons in its nucleus.

What does the atomic number of potassium indicate about its nucleus?

The number of protons in its nucleus.

Why did JJ Thomas conclude in $1897$ that atoms were not solid spheres?

His measurements showed the existence of smaller negatively charged particles (electrons).

In the plum pudding model, what represents the negatively charged particles stuck inside?

Electrons.

What charge did JJ Thomas attribute to the main sphere of the atom in the plum pudding model?

A positive charge.

Why did scientists expect alpha particles to pass through the gold foil with minimal deflection under the plum pudding model?

Because the positive charge was thought to be spread out throughout the atom rather than concentrated.

What evidence from Rutherford's experiment indicated that positive charge is concentrated in a tiny central area?

Some particles were deflected more than expected, and a small number were deflected backwards.

What evidence from Rutherford's experiment showed that most of the atom is empty space?

Most of the positively charged particles went straight through the thin sheet of gold.

According to Rutherford, where is the vast majority of an atom's mass concentrated?

In the nucleus at the centre.

What forms the outer region surrounding the nucleus in Rutherford's nuclear model?

A cloud of negatively charged electrons.

What is the relative mass value given for a proton in the notes?

$1$.

What is the relative mass value given for a neutron in the notes?

$1$.

What is the relative mass value given for an electron in the notes?

$0.0005$.

What is the charge value given for a proton in the notes?

$+1$.

What is the charge value given for a neutron in the notes?

$0$.

What is the charge value given for an electron in the notes?

$-1$.

In John Dalton's $1803$ proposal, what geometric form did he attribute to atoms?

Solid spheres.

According to Dalton, how do spheres of different elements compare?

Different spheres are made up of different elements.

What year marks the proposal of the plum pudding model by JJ Thomas?

In $1897$.

What year marks the alpha particle scattering experiment conducted by Ernest Rutherford?

In $1909$.

What thin metallic foil was used in the $1909$ scattering experiment?

A thin sheet of gold.

What type of charged particles were fired at the gold foil by Rutherford?

Positively charged particles.

What proportion of particles were deflected backwards during Rutherford's experiment?

A small number.

What proportion of particles passed through the gold foil during Rutherford's experiment?

Most of the particles.

How did Rutherford describe the physical size of the nucleus?

As a tiny nucleus at the centre.

What surrounds the tiny central nucleus in Rutherford's model?

A cloud of negatively charged electrons.

What constitutes the majority of an atom's volume in the nuclear model?

Empty space.

Which scientist's name appears directly after Ernest Rutherford at the end of the notes?

Niels Bohr.

What subatomic components make up the dense core at the centre of an atom?

Protons and neutrons.

What subatomic particles spread out around the edge of an atom according to Page 1?

Electrons.

Why is an atom neutral when it contains equal numbers of protons and electrons?

Because the $+1$ charge of each proton cancels out the $-1$ charge of each electron.

What is the formula representing the equality of charged particles in an atom?

$\text{protons} = \text{electrons}$.

What two subatomic particle types are added together to find an element's atomic mass?

Protons and neutrons.

What single subatomic particle type is counted to determine an element's atomic number?

Protons.

What statement do the notes make regarding the amount of protons in different elements?

Each element has a particular amount of protons.

How did John Dalton's $1803$ model depict atomic structure?

As solid spheres where different spheres represent different elements.

What key discovery did JJ Thomas make in $1897$ regarding the atom's internal structure?

He discovered smaller negatively charged particles (electrons), proving atoms were not solid spheres.

What did the plum pudding model propose about the distribution of positive and negative charges?

It proposed a ball of positive charge with negatively charged electrons stuck inside it.

What did Rutherford's alpha particle scattering experiment disprove?

The plum pudding model.

What did Rutherford's nuclear model replace?

JJ Thomas's plum pudding model.

Where is the cloud of negatively charged electrons found in Rutherford's model?

Surrounding the nucleus.

What did backward particle deflections in the scattering experiment prove about the nucleus?

That there is a tiny, dense, positively charged nucleus at the centre concentrating most of the atom's mass.

What is the chronological progression of scientists listed in the history of the atom notes?

John Dalton ($1803$), JJ Thomas ($1897$), Ernest Rutherford ($1909$), and Niels Bohr.