Chapter 4 Atomic Structure

All matter is composed of small, indestructible particles called atoms

Dalton's Atomic Theory

This person believed that atoms were indivisible and indestructible

Democritus

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

Electrons

What are the three types of subatomic particles?

Electrons, protons, neutrons

Why are elements different?

Elements are different from other types of elements because they contain different numbers of protons

Why do isotopes have different mass numbers?

Elements have different masses from other elements because they contain extra neutrons in their nucleus.

What is the mass number for an oxygen atom that has 9 neutrons in its nucleus?

Find Oxygen on the periodic table of elements. Add it's atomic number, which equals the number of its protons, to the 9 neutrons. 8+9 = 17. The answer is: Oxygen-17.

What is the mass number for a sodium atom that has 10 neutrons in its nucleus?

Find Sodium (Na) on the periodic table of elements. Add it's atomic number, which equals the number of its protons, to the 10 neutrons. 11+10 = 21. The answer is: Sodium-21. Gold Star.

Use the periodic table of elements to determine the number of electrons in a neutral atom of Bromine?

Neutral atoms have the same number of positive protons as they have negative electrons. Bromine is found to be element symbol Br and has an atomic number of 35. The atomic number is equal to the number of protons which is also equal to the number of electrons. Therefore, a neutral atom of Bromine has 35 electrons.

How many protons are present in an atom of Be-9?

The number 9 in Be-9 is a mass number and does not tell you the number of protons, instead, you can simply find the symbol Be as Beryllium on the periodic table. Beryllium (Be) has an atomic number of 4 which means that an atom of Be-9 has 4 Protons.

Smallest unit of matter

atom

The average mass of all atoms of an element

atomic mass

The number of protons in an atom; the number that identifies an element

atomic number

a beam of electrons emitted by the cathode of an electrical discharge tube

cathode ray

ability to rust, reactivity with acid, flammability

chemical properties

The number at the beginning of a chemical formula that tells you the number of molecules

coefficient

The outer portion of an atom that contains electrons; where most of the volume of an atom is located

electron cloud

The distance of electrons in the electron cloud from the nucleus; the 1st 3 levels can hold 2, 8, and 8 (also known as shells)

energy level

Isotope Symbol

form: mass on top, number of protons on bottom, and element symbol.

Atoms of the same element that have different numbers of neutrons

isotopes

Mass cannot be created or destroyed; reactants must equal products

law of conservation of mass

The rounded mass of an atom; protons + neutrons

mass number

Neutrally charged subatomic particles with a mass of 1 amu; located in the nucleus

neutron

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

neutrons and protons

The center of the atom that contains neutrons and protons; where most of the mass of an atom is located

nucleus

An arrangement of elements in columns, based on a set of properties that repeat from row to row

periodic table

shape, size, position, texture, ductile, malleable, brittle, state of matter

physical properties

The chemical formula(s) on the right side of the chemical equation

products

Positively charged subatomic particles with a mass of 1 amu; located in the nucleus

proton

The chemical formula(s) on the left side of the chemical equation

reactants

Scientists can observe individual atoms by

using instruments such as scanning tunneling microscopes

Subscript

Text that is reduced in size and lowered to the bottom of the current line.

Superscript

Text that is reduced in size and raised to the top of the current line.

An element has an atomic number of 42. The number of protons and electrons in a neutral atom of the element are:

The atomic number of any element tells you the number of protons and electrons in a neutral atom of that element. Atomic Number = Number of Protons = Number of Electrons p = 42, e = 42

How many protons are present in an atom of Ag-111?

The number 111 in Ag-111 is a mass number and does not tell you the number of protons, instead, you can simply find the symbol Ag as silver on the periodic table. Silver (Ag) has an atomic number of 47 which means that an atom of Ag-111 has 47 Protons.

Atomic Mass Unit

A unit of mass that describes the mass of an atom or molecule. (amu)

Atomic Nucleus

An atom's central core, containing protons and neutrons. (The Nucleus has a net positive charge because it is composed of positive protons and neutral neutrons).

How many protons are present in an atom of Zn-70?

The number 70 in Zn-70 is a mass number and does not tell you the number of protons, instead, you can simply find the symbol Zn as Zinc on the periodic table. Zinc (Zn) has an atomic number of 30 which means that an atom of Zn-70 has 30 Protons.

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

The number 84 represents that atomic mass of this isotope of krypton. It tells us that the

He transformed Democritus ideas about atoms into a scientific theory

Dalton

Use the periodic table of elements to determine the number of electrons in a neutral atom of Potassium?

Neutral atoms have the same number of positive protons as they have negative electrons. Potassium is found to be element symbol K and has an atomic number of 19. The atomic number is equal to the number of protons which is also equal to the number of electrons. Therefore, a neutral atom of Potassium has 19 electrons.

Calculate the number of neutrons in ¹³C.

Number of Neutrons = atomic# - mass# Carbon (C) can be found on the periodic table to have an atomic number of 6. Therefore, Number of Neutrons = 13 - 6 Number of Neutrons = 7

How many neutrons are present in an atom of the isotope ²⁴⁹₉₉Es?

Number of Neutrons = mass# - atomic# Einsteinium (Es) is shown to have an atomic number of 99. Therefore, Number of Neutrons = 249 - 99 Number of Neutrons = 150

How many neutrons are present in an atom of the isotope ²¹³₈₂Pb?

Number of Neutrons = mass# - atomic# Lead (Pb) is shown to have an atomic number of 82. Therefore, Number of Neutrons = 213 - 82 Number of Neutrons = 151

Calculate the number of neutrons in ¹²²Sn.

Number of Neutrons = mass# - atomic# Tin (Sn) can be found on the periodic table to have an atomic number of 50. Therefore, Number of Neutrons = 122 - 50 Number of Neutrons = 72

Calculate the number of neutrons in ¹⁸⁰W.

Number of Neutrons = mass# - atomic# Tungsten (W) can be found on the periodic table to have an atomic number of 74. Therefore, Number of Neutrons = 180 - 74 Number of Neutrons = 106

What is the mass number for an oxygen atom that has 10 neutrons in its nucleus?

Oxygen can be found on the periodic table of elements as O with an atomic number of 8. Number of Neutrons = Mass# - Atomic# 10 Neutrons = Mass# - Atomic Number-8 Mass# = 10 + 8 Mass# = 18

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

The number of protons and electrons is equal to the atomic number 45. The number of neutrons can be found as the difference between the atomic number and the mass number. # of neutrons = mass number - atomic number # of neutrons = 92 - 45 = 47 # of neutrons = 47 p = 45 e = 45 n = 47

How many protons, electrons, and neutrons does an atom with atomic number 5 and mass number 11 contain?

The number of protons and electrons is equal to the atomic number 5. The number of neutrons can be found as the difference between the atomic number and the mass number. # of neutrons = mass number - atomic number # of neutrons = 11 - 5 = 6 # of neutrons = 6 p = 5 e = 5 n = 6