What does the discovery that elements always combine in the same ratios mean for chemistry?

We can predict how elements will combine into compounds

Our current understanding of the atom is described best as:

A cloud of electrons around a nucleus of protons & neutrons

Aristotle's alchemical model reigned for over 2000 years despite knowledge of the atom. Why?

He was the most respected and believed philosopher

How did Chadwick's discovery of the neutron solve Rutherford's mass problem?

It accounted for the extra mass in the atomic mass

The phlogiston theory was added to alchemy because alchemy could not explain what?

Why wood lost mass when it burned

Scientists use models to explain ideas. Which of these is a characteristic of a good model?

It is simple; conveys only one or two ideas, It is concise (to the point) and easy to understand

Proust developed the Law of Constant Composition, which says what?

Elements always combine in the same ratios to form compounds

Why did Bohr's Quantum Mechanical model struggle to gain acceptance amongst physicists?

It required belief in a branch of physics Bohr had invented

Which of these is a disadvantage of scientific models?

They demonstrate ideas but do not represent reality

Lavoisier's tin experiment is the reason we balance chemical reactions. What did he prove?

The mass of the reactants and products must be equal

Rutherford's gold foil experiment shot alpha particles at gold foil. What did this prove?

Existence of a large, heavy mass in the atom's center

Bohr's model suggested the "quantum leap", which is when what happens?

Electrons fall back to lower energy levels and emit photons

According to the Modern Atomic Theory, which of these is NOT true?

Matter can be converted from one element into another

The huge, glaring flaw that Rutherford could never solve with his Nuclear Model was which?

The difference between atomic number and atomic mass

Which of these is the only tenet of Dalton's atomic theory we do not still use?

All atoms of an element have the same mass and properties

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Atomic Theory Review

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#O'Hair Review questions for the final exam covering atomic theory

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Questions 20

Answers

1
What does the discovery that elements always combine in the same ratios mean for chemistry?
Elements are all made of the same particles
Elements combine in unknowable ways
We can predict how elements will combine into compounds
Compounds are all made from equal numbers of elements
2
Our current understanding of the atom is described best as:
Electrons orbiting the nucleus like planets
A cloud of electrons around a nucleus of protons & neutrons
A blob of positive charge with electrons embedded in it
A solid ball of matter
3
Aristotle's alchemical model reigned for over 2000 years despite knowledge of the atom. Why?
He was the most respected and believed philosopher
The inventor of the atom theory had been arrested for heresy
Microscopic studies had proven the atom wrong
His theory had been proven correct
4
How did Chadwick's discovery of the neutron solve Rutherford's mass problem?
It accounted for the extra mass in the atomic mass
It proved the electrons did not occupy the nucleus
It had no bearing on Rutherford's model
It proved radiation was possible
5
The phlogiston theory was added to alchemy because alchemy could not explain what?
Why atoms were so small
Why electrons could not exist in the nucleus
Why matter could not be created or destroyed
Why wood lost mass when it burned
6
JJ Thompson discovered the first subatomic particle, disproving Dalton's model. Which was it?
Electron
Neutron
Hadron
Proton
7
Scientists use models to explain ideas. Which of these is a characteristic of a good model?
It came from a reputable modelling agency
It explains many ideas at once
It is simple; conveys only one or two ideas
It is concise (to the point) and easy to understand
8
Proust developed the Law of Constant Composition, which says what?
Atoms are always made from protons, neutrons, and electrons
Elements always combine in the same ratios to form compounds
All matter is made of atoms
Compounds are always made out of the same elements
9
Because Dalton's model was wrong, Thompson replaced it with what?
Orbiting Electron model
Plum Pudding model
Quantum Mechanical model
Nuclear Atom model
10
Why did Bohr's Quantum Mechanical model struggle to gain acceptance amongst physicists?
It described an atom that could not exist in 3 dimensions
It required belief in a branch of physics Bohr had invented
It still did not explain why electrons were so small
Bohr had not calculated the angular velocity of the atom
11
When was the idea of the "atom" first theorized?
18th century France
Ancient Greece
17th century Germany
5th century Iran
12
Which of these is a disadvantage of scientific models?
They are always difficult to make
They demonstrate ideas but do not represent reality
You need to understand the idea to understand the model
They are always too complicated for lay-people to understand
13
Antoine Lavoisier disproved these two atomic theories with his famous tin experiment
Phlogiston and the plum pudding model
Phlogiston and alchemy
the quantum mechanical theory and the nuclear thoery
The nuclear theory and alchemy
14
Lavoisier's tin experiment is the reason we balance chemical reactions. What did he prove?
The mass of the reactants must be equal
The mass of the reactants and products must be equal
The number of protons must equal the number of electrons
The mass of the products must be equal
15
Rutherford's gold foil experiment shot alpha particles at gold foil. What did this prove?
Rutherford had too much free time
The sea of electrons
Existence of a large, heavy mass in the atom's center
Gold was an excellent conductor of heat and electricity
16
Bohr's model suggested the "quantum leap", which is when what happens?
An electron leaps forward or backward in time
A proton leaps to the opposite side of the nucleus
Neutrons leap from nucleus as radiation
Electrons fall back to lower energy levels and emit photons
17
According to the Modern Atomic Theory, which of these is NOT true?
Matter cannot be divided into smaller pieces
Matter can be converted from one element into another
Matter cannot be created
Matter cannot be destroyed
18
Which of these describes Dalton's atomic model?
The Quantum Mechanical model
The Plum Pudding model
A solid sphere
A solar system model where electrons orbit the nucleus
19
The huge, glaring flaw that Rutherford could never solve with his Nuclear Model was which?
Why group B metals formed many ions, but not group A metals
Why the atom rotated when placed in an electrical field
The difference between atomic number and atomic mass
Where the electrons sat in the atom
20
Which of these is the only tenet of Dalton's atomic theory we do not still use?
Elements combine in simplest integer ratios in compounds
All atoms of an element have the same mass and properties
Atoms cannot be destroyed
Atoms cannot be created

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