Chapter 7 Science Test Flashcards

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1
Q

How many elements were identified by the late 1700’s?

A

• More than 30 elements

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2
Q

Who proposed an atomic theory of matter?

A

• John Dalton in 1808

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3
Q

Who was the first person to envision the atom?

A

• Democritus

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4
Q

How did John Dalton envision the atom?

A

• A small smooth solid sphere without an electric charge

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5
Q

What was Dalton’s Theory?

A

• All matter is made of atoms, which are particles too
small to see
• Each element has its own kind of atom, with its own
particular mass
• All atoms of any one element are identical
• Compounds are created when atoms of different
elements combine in a specific ratio
• Atoms cannot be created, destroyed, or subdivided
during chemical changes

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6
Q

Who discovered what that led to changes in Dalton’s Theory?

A

• Michael Faraday showed that atoms could gain

electric charges

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7
Q

What Revisions were made to Dalton’s Theory?

A

• Matter must contain positive and negative charges
• Opposite charges attract, and like charges repel
• Atoms combine to form the particles of a compound
because of the electrical attractions between charged
atoms

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8
Q

When was the electron discovered, and who discovered it?

A

• The electron was discovered in 1898 by J.J Thomson

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9
Q

What was Thomson’s Revision to the Atomic Theory?

A

• Atoms contain electrons
• The electrons have a negative charge and a very small
mass
• The rest of the atom has a positive charge
• The electrons are embedded randomly in the positive
part of the atom
• Electrons can be removed from, or added to, atoms to
create charged atoms

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10
Q

What was Thomson’s model called?

A

• Raisin-bun model

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11
Q

How did Rutherford attempt to probe the structure of an atom?

A

• He bombarded a very thin piece of gold foil with small,
positively charged particles
• He expected most of the particles to be deflected, as
predicted by Thomson’s revision

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12
Q

What did Rutherford’s discovery lead to?

A

• Rutherford’s Nuclear model

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13
Q

What are Rutherford’s Revisions to the Atomic Theory?

A

• The nucleus contains all of the positive charge and
most of the mass of the atom
• The nucleus contains positively charged protons and
uncharged neutrons.
• Neutrons have the same mass as protons
• The nucleus is very small, compared with the size of
the atom
• The mass of an electron is 1/1800 the mass of a proton
• The size of the atom is determined by the size of the
orbit of the electron
• There is only empty space between the electrons and
the nucleus

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14
Q

Why did Rutherford know his theory was not completely correct?

A

• A well-established theory of electromagnetic waves
predicted that Rutherford’s orbiting electrons should
continuously emit energy, which they do not.

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15
Q

What happens when atoms absorb electrical or heat energy?

A

• They re-emit the energy as light
• Each element emits a very specific pattern of
wavelengths, or colours, of light, called the emission
spectrum

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16
Q

How did Niels Bohr solve the problems of Rutherford’s model of the atom?

A

• He used the emission spectrum of the element and

discoveries of other scientists.

17
Q

What was Albert Einstein’s observation that Bohr used?

A

• Albert Einstein had shown that atoms can only absorb
or emit light energy in specific amounts
• Bohr used this to observation to explain why the
electrons orbiting the nucleus do not continuously give
of energy

18
Q

What are electron shells?

A

• Specific orbits in which electrons circle the nucleus,

electrons cannot exist in between shells

19
Q

How is the energy of a electron determined?

A

• Based on it’s distance from the nucleus

20
Q

Why does each element have an unique pattern of light emission?

A

• Because its unique separation of its allowed electron

shells

21
Q

When can atoms absorb or emit light energy?

A

• When they jump between shells

22
Q

What are Bohr’s Revisions to the atomic Theory?

A

• Electrons are located in defined shells, which are
located certain distances from the nucleus
• Electrons cannot exist between the defined shells
• Electrons can gain energy to move up to a higher shel,
or they can lose energy to move down to a lower shell
• Electrons are more stable (have less energy) when
they are closer to the nucleus