Chemistry Chapter 4 Flashcards

Questions and Answers

What did Democritus reason about atoms?

Atoms were indivisible and indestructible.

What is an atom?

The smallest particle of an element that retains its identity in a chemical reaction.

Who transformed Democritus' ideas on atoms into a scientific theory?

Dalton.

What does Dalton's first atomic theory state?

All elements are composed of tiny indivisible particles. Signup and view all the answers

What does Dalton's second atomic theory state?

Atoms of the same element are identical; the atoms of any one element are different from those of another. Signup and view all the answers

What does Dalton's third atomic theory state?

Atoms of different elements can physically mix together or can chemically combine in simple whole number ratios to form compounds. Signup and view all the answers

What does Dalton's fourth atomic theory state?

Chemical reactions occur when elements are separated from each other, joined, or rearranged in a different combination. Signup and view all the answers

What are electrons?

Negatively charged subatomic particles. Signup and view all the answers

What was the experiment performed by Thomson?

The Cathode Ray experiment. Signup and view all the answers

What was the outcome of Thomson's experiment?

One electrode became positively charged, one became negative, resulting in a glowing beam. Signup and view all the answers

Who carried out the oil drop experiment?

Robert A. Millikan. Signup and view all the answers

What is the charge of an electron?

One unit of negative charge. Signup and view all the answers

What is the mass of an electron?

1/1840. Signup and view all the answers

What is the charge of a proton?

1+. Signup and view all the answers

What is the charge of a neutron?

<ol start="0"> <li></li> </ol> Signup and view all the answers

What discovery is associated with Thomson?

The electrons. Signup and view all the answers

What is the Thomson model of the atom known as?

Plum pudding model. Signup and view all the answers

What was Rutherford's significant experiment?

The gold foil experiment. Signup and view all the answers

What is the nucleus of an atom?

Tiny central core composed of protons and neutrons. Signup and view all the answers

What does the nuclear atom model suggest?

It has a positively charged nucleus with electrons distributed around it. Signup and view all the answers

How are elements different from each other?

They all contain a different number of protons. Signup and view all the answers

What is the atomic number?

The number of protons in that element. Signup and view all the answers

What is the mass number?

The total number of protons and neutrons. Signup and view all the answers

What are isotopes?

Atoms that have the same number of protons but different numbers of neutrons. Signup and view all the answers

Why do isotopes have different mass numbers?

Because they have a different number of neutrons. Signup and view all the answers

What is an atomic mass unit (amu)?

1/12 of the mass of a carbon atom. Signup and view all the answers

What is the definition of atomic mass?

Weighted average mass of the atoms in a naturally occurring sample of the element. Signup and view all the answers

How do you calculate atomic mass?

Mass of each isotope multiplied by its natural abundance, and then add the products. Signup and view all the answers

Study Notes

Democritus and Atomic Theory

Democritus proposed that atoms are indivisible and indestructible, laying the groundwork for atomic theory.
John Dalton expanded on Democritus' ideas, formulating Dalton's Atomic Theory, which consists of several key postulates.

Dalton's Atomic Theory

All elements are made of tiny indivisible particles called atoms.
Atoms of the same element are identical, while atoms of different elements differ.
Atoms can mix physically or combine chemically in simple whole-number ratios to form compounds.
Chemical reactions involve the separation, joining, or rearrangement of atoms.

Subatomic Particles

Electrons are negatively charged subatomic particles, fundamental to atomic structure.
Protons carry a positive charge, while neutrons have no charge.

Historical Experiments

J.J. Thomson conducted cathode ray experiments, revealing the existence of electrons, leading to his plum pudding model of atomic structure.
Robert A. Millikan's oil drop experiment determined the charge of an electron as one unit of negative charge.

Atomic Structure

The nucleus is the atom's dense central core, composed of protons and neutrons.
A nuclear atom has a positively charged nucleus with electrons distributed around it, constituting most of the atom's volume.

Atomic Identity

The atomic number signifies the number of protons in an element and determines its uniqueness.
Mass number is the total number of protons and neutrons in an atom's nucleus.
Isotopes are variants of the same element with identical proton counts but different neutron counts, resulting in varied mass numbers.

Atomic Mass

Atomic mass unit (amu) represents 1/12 of the mass of a carbon atom.
Atomic mass is the weighted average mass of an element's isotopes based on their natural abundance.
To calculate atomic mass, multiply the mass of each isotope by its natural abundance and sum the results.

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Test your knowledge with these flashcards from Chemistry Chapter 4. Explore fundamental concepts such as atoms, Democritus's ideas, and Dalton's Atomic Theory. Perfect for students looking to reinforce their understanding of atomic theory.