Chemistry Chapter 4 Atomic Structure

Questions and Answers

What is the smallest unit of matter?

atom

What is the center of the atom that contains neutrons and protons?

nucleus

What is the outer portion of an atom that contains electrons?

electron cloud

What are neutrally charged subatomic particles located in the nucleus called?

neutron Signup and view all the answers

What are the positively charged subatomic particles located in the nucleus called?

proton Signup and view all the answers

What is the average mass of all atoms of an element called?

atomic mass Signup and view all the answers

What is the rounded mass of an atom that includes protons and neutrons?

mass number Signup and view all the answers

What does the atomic number represent?

number of protons Signup and view all the answers

What is the form of the Isotope symbol?

mass on top, number of protons on bottom, and element symbol Signup and view all the answers

What is text that is reduced in size and lowered to the bottom of the current line?

subscript Signup and view all the answers

What is text that is reduced in size and raised to the top of the current line?

superscript Signup and view all the answers

What do you call the distance of electrons in the electron cloud from the nucleus?

energy level Signup and view all the answers

What are the chemical formula(s) on the left side of the chemical equation called?

reactants Signup and view all the answers

What are the chemical formula(s) on the right side of the chemical equation called?

products Signup and view all the answers

What is the law that states mass cannot be created or destroyed?

law of conservation of mass Signup and view all the answers

What is the number at the beginning of a chemical formula that tells you the number of molecules?

coefficient Signup and view all the answers

What are some examples of chemical properties?

ability to rust, reactivity with acid, flammability Signup and view all the answers

What are examples of physical properties?

shape, size, position, texture, ductile, malleable, brittle, state of matter Signup and view all the answers

What is a beam of electrons emitted by the cathode of an electrical discharge tube called?

cathode ray Signup and view all the answers

What does Dalton's Atomic Theory state?

All matter is composed of small, indestructible particles called atoms Signup and view all the answers

What are atoms of the same element that have different numbers of neutrons called?

isotopes Signup and view all the answers

What is an arrangement of elements in columns based on repeating properties called?

periodic table Signup and view all the answers

Who believed that atoms were indivisible and indestructible?

Democritus Signup and view all the answers

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

Dalton Signup and view all the answers

How can scientists observe individual atoms?

using instruments such as scanning tunneling microscopes Signup and view all the answers

What are the three types of subatomic particles?

electrons, protons, neutrons Signup and view all the answers

Which subatomic particles are found in the nucleus of an atom?

neutrons and protons Signup and view all the answers

Which subatomic particles are distributed around the edge of the atom?

electrons Signup and view all the answers

Why are elements different?

Elements contain different numbers of protons Signup and view all the answers

Why do isotopes have different mass numbers?

Isotopes contain extra neutrons in their nucleus Signup and view all the answers

If an element has an atomic number of 42, what are the numbers of protons and electrons in a neutral atom of that element?

p = 42, e = 42 Signup and view all the answers

What does the number 84 in the name krypton-84 represent?

the atomic mass of this isotope of krypton Signup and view all the answers

How many protons, electrons, and neutrons does an atom with atomic number 45 and mass number 92 contain?

p = 45, e = 45, n = 47 Signup and view all the answers

Study Notes

Atomic Structure Overview

An atom is the smallest unit of matter.
The nucleus is at the atom's center, housing neutrons and protons, where most of an atom's mass is found.
The electron cloud surrounds the nucleus and contains electrons, representing most of the atom's volume.

Subatomic Particles

Neutrons: Neutrally charged, located in the nucleus, with a mass of 1 amu.
Protons: Positively charged, located in the nucleus, with a mass of 1 amu.
Electrons: Negatively charged particles that exist in the electron cloud.

Atomic Mass and Structure

Atomic mass is the average mass of an element's atom.
Mass number is the sum of protons and neutrons in an atom.
Atomic number identifies the element based on the number of protons.

Isotopes and Symbols

Isotopes have the same number of protons but different numbers of neutrons.
Isotope Symbol consists of mass on top, atomic number on the bottom, and element symbol.

Chemical and Physical Properties

Chemical properties include reactivity, flammability, and the ability to rust.
Physical properties include shape, size, texture, and state of matter.

Chemical Equations

Reactants are the formulas on the left side of a chemical equation.
Products are the formulas on the right side of a chemical equation.
The law of conservation of mass states mass cannot be created or destroyed; reactants must equal products.

Fundamental Concepts

Coefficients indicate the number of molecules in a chemical formula.
Energy levels refer to the distance of electrons from the nucleus, with the first three levels capable of holding 2, 8, and 8 electrons.

Historical Background

According to Dalton's Atomic Theory, all matter is composed of indivisible atoms.
Democritus first proposed the idea of indivisible atoms, later scientifically expanded by Dalton.

Practical Applications

Individual atoms can be observed using scanning tunneling microscopes.
Understanding atomic structure helps explain why elements differ, primarily due to their unique numbers of protons.

Atomic Composition

For an element with atomic number 42, it contains 42 protons and electrons in a neutral atom.
An isotope like krypton-84 has an atomic mass of 84.
For an atom with atomic number 45 and mass number 92, it has 45 protons, 45 electrons, and 47 neutrons.

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Test your knowledge of atomic structure with these flashcards covering key terms and definitions from Chapter 4. Learn about atoms, nuclei, electron clouds, and more essential concepts in chemistry.