Chemistry Chapter 4: Atomic Structure Flashcards

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Questions and Answers

What does Democritus's Atomic Theory state about matter?

Matter is composed of empty space through which atoms move. (correct)

Matter is composed of elements that cannot be divided.

Different atoms have the same sizes and shapes.

Atoms are only made of solid materials.

Which of the following is NOT a part of Dalton's Atomic Theory?

Atoms of the same element are identical.

Atoms can be created or destroyed. (correct)

All matter is composed of atoms.

Different atoms combine in whole number ratios.

Why is Dalton's atomic theory slightly wrong?

Atoms can have slightly different masses and are divisible into smaller subatomic particles.

What is an atom?

The smallest particle of an element. Signup and view all the answers

What is a cathode ray?

A beam of electrons emitted by the cathode of an electrical discharge tube. Signup and view all the answers

What is an anode?

A positively charged electrode by which electrons leave an electrical device. Signup and view all the answers

What is an electron?

A negatively charged particle located outside the atomic nucleus. Signup and view all the answers

Who determined the charge of the electron?

Robert Milikan. Signup and view all the answers

What was discovered by J.J. Thomson in 1897?

Electrons using cathode ray and positively charged plates. Signup and view all the answers

The mass of an electron is ___.

1/1840 Signup and view all the answers

What does the plum pudding model suggest?

Negatively charged electrons are distributed throughout a uniform positive charge. Signup and view all the answers

What does Rutherford's nuclear atomic model explain?

The results of the gold foil experiment. Signup and view all the answers

What are protons?

Positively charged particles in the atomic nucleus. Signup and view all the answers

The mass of a proton is ___.

1 Signup and view all the answers

What is the atomic number?

The number of protons in the nucleus of an atom. Signup and view all the answers

What is the mass number?

The sum of the number of neutrons and protons in an atomic nucleus. Signup and view all the answers

What are isotopes?

Atoms of the same element that have different numbers of neutrons. Signup and view all the answers

What is average atomic mass?

Weighted average of the atomic masses for the isotopes of an element. Signup and view all the answers

What is radioactivity?

The process in which some substances spontaneously emit radiation. Signup and view all the answers

Alpha radiation is made up of ___ particles.

alpha Signup and view all the answers

What is a nuclear equation?

A type of equation that shows the atomic number and mass number of the particles involved. Signup and view all the answers

What is transmutation?

The process of changing one element to another through radioactive decay. Signup and view all the answers

What is the difference between chemical reactions and nuclear reactions?

Chemical reactions involve changes in the electrons surrounding the atom; nuclear reactions involve changes in the nucleus of the atom. Signup and view all the answers

What are gamma rays?

Consist of high energy protons with no rest mass or charge. Signup and view all the answers

Study Notes

Democritus's Atomic Theory

Matter consists of empty space allowing atom movement.
Atoms are solid, homogeneous, indestructible, and indivisible.
Varying shapes and sizes of atoms account for different matter properties.

Dalton's Atomic Theory

All matter is made of tiny atoms.
Atoms of an element are identical in size and mass; different elements have different atoms.
Atoms cannot be created, divided, or destroyed.
Atoms combine in simple whole-number ratios to form compounds.
During chemical reactions, atoms are rearranged.

Limitations of Dalton's Theory

Recognizes that atoms have slightly different masses and are divisible into subatomic particles.

Atom Definition

The smallest particle of an element which retains its chemical identity.

Cathode Ray

A beam of electrons produced by the cathode in an electrical discharge tube.

Cathode

The negatively charged electrode from which electrons are emitted.

Anode

The positively charged electrode through which electrons exit the device.

Electron

A negatively charged particle located outside the atomic nucleus.

Robert Milikan

Known for measuring the charge of the electron.

J.J. Thomson

Discovered electrons in 1897 using cathode rays and positively charged plates; proposed the "plum pudding model."

Mass of an Electron

Approximately 1/1840 of a proton's mass.

Plum Pudding Model

Suggests electrons are spread within a uniform positive charge.

Rutherford's Nuclear Atomic Model

Based on gold foil experiment results; alpha particles mostly pass through with minor deflections.
Identified a dense positive nucleus responsible for deflections of alpha particles.

Proton

A subatomic particle with a positive charge, essential to atomic structure, discovered by Rutherford.

Mass of a Proton

Proton's mass is approximately 1 atomic mass unit (amu).

Neutron

A subatomic particle with no electrical charge, identical mass to a proton.

Electron Cloud

A probability region around an atomic nucleus where electrons are likely found.

Atomic Number

Indicates the number of protons in an atom's nucleus, determining the element's identity.

Mass Number

Total count of protons and neutrons in an atomic nucleus.

Isotopes

Variations of the same element differing in neutron count.

Average Atomic Mass

A weighted average reflecting the atomic mass of isotopes based on their abundance.

Atomic Mass Unit (amu)

Defined as one-twelfth the mass of a carbon-12 atom.

Atomic Mass

The average of the mass numbers of an element's isotopes.

Nuclear Reactions

Involve splitting or fusing atomic nuclei, producing significant energy compared to chemical reactions.

Radioactivity

The spontaneous emission of radiation from certain substances.

Radiation

Energy emitted in the form of rays, waves, or particles.

Radioactive Decay

The release of nuclear particles and energy from unstable atomic nuclei.

Alpha Radiation

Composed of alpha particles, deflected toward a negatively charged plate in electric fields.

Alpha Particles

Formed from two protons and two neutrons; equivalent to a helium-4 nucleus.

Alpha Particle Properties

Largest radioactive particle with limited range; most damaging due to mass.

Nuclear Equations

Represent changes involving atomic and mass numbers in radioactive processes.

Beta Radiation

Involves the emissions of beta particles during decay.

Beta Particles

Electrons emitted from neutron decay; low mass and charge of -1, moderate penetrating power.

Effects of Alpha Particle Emission

Results in a decrease of mass number by 4 and atomic number by 2.

Conservation in Nuclear Equations

Mass numbers and atomic numbers must balance on both sides of the equation.

Beta Decay Process

A neutron converts into a proton and emits an electron, leaving the mass number unchanged while increasing the atomic number by 1.

Transmutation

The transformation of one element into another via radioactive decay.

Chemical vs. Nuclear Reactions

Chemical reactions affect electron arrangements; nuclear reactions involve changes in the atomic nucleus.

Gamma Rays

High-energy electromagnetic radiation with no mass or charge; highly penetrating and not deflected in fields.

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Description

Explore key concepts from Chapter 4 on the structure of the atom with these flashcards. Dive into the theories of Democritus and Dalton, learning about the nature and behavior of atoms. Test your understanding of atomic theory and its foundational role in chemistry.