Ch.2 - Atoms & ElementsWorksheetSee all chapters
All Chapters
Ch.1 - Intro to General Chemistry
Ch.2 - Atoms & Elements
Ch.3 - Chemical Reactions
BONUS: Lab Techniques and Procedures
BONUS: Mathematical Operations and Functions
Ch.4 - Chemical Quantities & Aqueous Reactions
Ch.5 - Gases
Ch.6 - Thermochemistry
Ch.7 - Quantum Mechanics
Ch.8 - Periodic Properties of the Elements
Ch.9 - Bonding & Molecular Structure
Ch.10 - Molecular Shapes & Valence Bond Theory
Ch.11 - Liquids, Solids & Intermolecular Forces
Ch.12 - Solutions
Ch.13 - Chemical Kinetics
Ch.14 - Chemical Equilibrium
Ch.15 - Acid and Base Equilibrium
Ch.16 - Aqueous Equilibrium
Ch. 17 - Chemical Thermodynamics
Ch.18 - Electrochemistry
Ch.19 - Nuclear Chemistry
Ch.20 - Organic Chemistry
Ch.22 - Chemistry of the Nonmetals
Ch.23 - Transition Metals and Coordination Compounds

Solution: Consider the stable elements through lead (Z=82).In how many instances are the atomic weights of the elements out of order relative to the atomic numbers of the elements?

Problem

Consider the stable elements through lead (Z=82).

In how many instances are the atomic weights of the elements out of order relative to the atomic numbers of the elements?

Solution

We’re asked to determine how many instances in the periodic table are the atomic weights of the elements out of order relative to the atomic numbers of the elements considering the stable elements through lead (Z=82).


Recall that elements in the periodic table are arranged in order of increasing atomic numbers


The first known periodic table was made by Mendeleev.  He arranged elements in order of increasing mass and observed that the physical and chemical properties of elements were related to their atomic mass in a 'periodic' way (arranged in periods/rows). 


We will examine using a periodic table, whether elements with atomic numbers 1 to 82 are arranged in order of increasing atomic mass along with an increasing atomic number, Z.

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