Atomic Structure and Models Quiz
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Questions and Answers

What is the relative atomic mass (R.A.M.) of chlorine calculated from its isotopes?

  • 34.5
  • 36.5
  • 35.5 (correct)
  • 35.0

What percentage of the chlorine sample is chlorine-37?

  • 70%
  • 30%
  • 25% (correct)
  • 50%

Which formula correctly represents the calculation used to determine the R.A.M. of chlorine?

  • (35 x 25) + (37 x 75) / 100
  • ((35 x 75) + (37 x 25)) / 100 (correct)
  • (35 x 75) + (37 x 25) / 100
  • (35 x 75) + (37 x 25)

If the abundance of chlorine-35 were 80% instead of 75%, what would the new R.A.M. of chlorine approximately be?

<p>35.8 (D)</p> Signup and view all the answers

What would happen to the R.A.M. if chlorine-37 were not present in the sample?

<p>It would be 35. (A)</p> Signup and view all the answers

What is the relative charge of a neutron?

<p>0 (C)</p> Signup and view all the answers

What is the mass number of an atom if it has 6 protons and 8 neutrons?

<p>14 (A)</p> Signup and view all the answers

How do isotopes of an element differ?

<p>Number of neutrons (C)</p> Signup and view all the answers

What primarily constitutes the mass of an atom?

<p>Nucleus (B)</p> Signup and view all the answers

Why do atoms contain an equal number of protons and electrons?

<p>To achieve a neutral charge (D)</p> Signup and view all the answers

What happens to the relative atomic mass of an element if it has different isotopes?

<p>It can vary and may not be a whole number (D)</p> Signup and view all the answers

What is the relationship between atomic number and the number of protons in an atom?

<p>The atomic number is equal to the number of protons (B)</p> Signup and view all the answers

How can the number of neutrons in an atom be calculated?

<p>Mass number - atomic number (A)</p> Signup and view all the answers

What defines the identity of an element?

<p>Number of protons (D)</p> Signup and view all the answers

What is the relative mass of an electron compared to a proton?

<p>1/1836 (C)</p> Signup and view all the answers

What was one of the key points of Dalton's atomic theory?

<p>All substances are made of atoms. (B)</p> Signup and view all the answers

What did J.J. Thomson discover using the cathode-ray tube?

<p>Atoms can be divided into smaller particles. (A)</p> Signup and view all the answers

Which model did J.J. Thomson propose?

<p>The plum-pudding model. (A)</p> Signup and view all the answers

What significant finding came from Rutherford's gold foil experiment?

<p>Most of the atom is empty space. (C)</p> Signup and view all the answers

According to Rutherford's model, what occupies the center of the atom?

<p>The nucleus. (B)</p> Signup and view all the answers

Which of the following statements about Dalton's atomic theory is incorrect?

<p>Atoms can be created. (B)</p> Signup and view all the answers

What did Rutherford conclude about the behavior of positively charged particles in his experiment?

<p>Some particles were deflected while others passed through. (B)</p> Signup and view all the answers

How did scientists' understanding of atoms change because of the discovery of subatomic particles?

<p>Atoms are composed of smaller units. (A)</p> Signup and view all the answers

What does the term 'plum-pudding model' refer to in atomic theory?

<p>A model depicting electrons scattered in a cloud. (B)</p> Signup and view all the answers

In what manner did Rutherford's model differ from Dalton's original theory?

<p>Rutherford indicated that atoms have a nucleus. (D)</p> Signup and view all the answers

Flashcards

Dalton's Atomic Theory

John Dalton proposed that all matter is made up of tiny, indivisible particles called atoms.

Atoms of the same element are identical.

Dalton's theory stated that atoms of the same element are identical, while atoms of different elements are different.

Atoms are indivisible.

Dalton's hypothesis that atoms cannot be created, divided, or destroyed was later disproved by the discovery of subatomic particles.

Discovery of Electrons

J.J. Thomson discovered negatively charged particles called electrons by studying cathode rays in a cathode-ray tube.

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Plum Pudding Model

Thomson's model compared the atom to a plum pudding, with negatively charged electrons embedded in a positively charged sphere.

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Rutherford's Gold Foil Experiment

Rutherford's gold foil experiment showed that most of the atom's mass and positive charge are concentrated in a small, dense center called the nucleus.

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Rutherford's Nuclear Model

Rutherford's model of the atom, based on his experiment, proposed that electrons orbit the nucleus in a vast, mostly empty space.

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Revision of Dalton's Atomic Theory

Dalton's theory was revised due to the discovery of subatomic particles like electrons and the nucleus.

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Atoms are divisible.

The discovery of subatomic particles showed that atoms are not indivisible, but rather are composed of smaller particles.

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Evolution of Atomic Models

The development of atomic models has evolved over time, starting with Dalton's simple model and progressing to more complex models.

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What is the nucleus of an atom?

A very small, dense region at the center of an atom containing protons and neutrons. It is positively charged due to the presence of protons.

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What are protons?

Subatomic particles found in the nucleus of an atom. They carry a positive charge of +1.

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What are neutrons?

Subatomic particles found in the nucleus of an atom. They are neutral, meaning they have no charge.

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What are electrons?

Negatively charged particles that orbit the nucleus of an atom in specific energy levels called shells.

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Why are atoms electrically neutral?

Atoms are electrically neutral because the number of protons (positive charges) equals the number of electrons (negative charges).

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What is the mass number of an atom?

The total number of protons and neutrons in the nucleus of an atom.

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What is the definition of an element based on its atomic structure?

Atoms of the same element have the same number of protons in their nucleus. This number is called the atomic number.

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What are isotopes?

Different atoms of the same element that have the same number of protons but different numbers of neutrons.

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Why are the relative atomic masses of some elements not whole numbers?

The relative atomic mass of an element is not always a whole number because it is an average mass calculated taking into account the abundance of different isotopes.

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What is relative atomic mass (RAM)?

The relative atomic mass (RAM) is the weighted average of the masses of all the isotopes of that element.

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What is percentage abundance of an isotope?

The percentage abundance of an isotope is the proportion of that isotope that is present in a natural sample of the element. For example, if 75% of a sample of chlorine is chlorine-35, then the percentage abundance of chlorine-35 is 75%.

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How is Relative Atomic Mass (RAM) calculated?

The RAM is calculated by multiplying the mass of each isotope by its percentage abundance, adding up the results, and then dividing by 100. This accounts for the different amounts of each isotope in a naturally occurring sample.

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Calculate the RAM of chlorine using the given data. (Chlorine-35, 75%, Chlorine-37, 25%)

Chlorine-35 and chlorine-37 are isotopes of chlorine. Chlorine-35 has a mass of 35 and an abundance of 75%, while chlorine-37 has a mass of 37 and an abundance of 25%. By using the formula for RAM: (mass of isotope 1 x % abundance of isotope 1) + (mass of isotope 2 x % abundance of isotope 2)/100, we get (35 x 75) + (37 x 25) /100 = 35.5.

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Study Notes

Atomic Structure

  • Atoms are the basic building blocks of matter
  • Atoms cannot be created, divided, or destroyed
  • Atoms of the same element are identical
  • Atoms join to make new substances

Dalton's Atomic Theory (1803)

  • All substances are made of atoms
  • Atoms of the same element are identical
  • Atoms of different elements are different
  • Atoms combine to form new substances

J.J. Thomson's Model (1897)

  • Atoms can be divided into smaller parts
  • Atoms contain negatively charged particles called electrons
  • Electrons are scattered throughout a positively charged "pudding"

Ernest Rutherford's Model (1909)

  • Atoms are mostly empty space
  • Most of the mass is concentrated in a tiny, dense nucleus
  • Electrons orbit the nucleus

Subatomic Particles

  • Proton: Positive charge, relative mass 1
  • Neutron: No charge, relative mass 1
  • Electron: Negative charge, relative mass 1/1836

Atomic Structure Summary

  • Atoms are composed of a nucleus containing protons and neutrons, surrounded by electrons in shells
  • Atoms have equal numbers of protons and electrons, resulting in a neutral charge
  • The nucleus is a very small region compared to the overall size of the atom
  • Most of the atomic mass is concentrated in the nucleus

Isotopes

  • Isotopes are atoms of the same element with the same number of protons but different numbers of neutrons
  • Isotopes have different mass numbers

Relative Atomic Mass (R.A.M)

  • An average of the masses of all the isotopes of an element, weighted by their relative abundance
  • R.A.M is not a whole number because it is an average
  • ¹²C is taken as the standard for comparison = 12

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Edexcel GCSE Chemistry Atomic Structure Notes PDF

Description

Test your knowledge on atomic structure and the historical models proposed by scientists like Dalton, Thomson, and Rutherford. This quiz covers the basic principles of atoms, their subatomic particles, and how they combine to form new substances. Perfect for students studying chemistry concepts related to atomic theory.

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