It’s in the Cards
Student Activity Kit
Materials Included In Kit
Element card decks, 6 sets
- Element Card Arrangement Handout: Make enough copies of this handout (see Teacher PDF) on regular paper to give each student an individual copy. After students have completed their own element arrangement on the worksheet, they will work from this handout to complete the questions and graphs on the “It’s in the Cards” Worksheet.
- Although this is a “dry-lab” activity, it is best to schedule enough time for it in class so that students can complete steps 1–6 in the Procedure section. This will ensure that students really do treat the lab as a discovery activity. Do not give students the Element Card Arrangement Handout until they have completed the Table of the Elements on the Data Sheet.
- Keeping in mind the spirit of discovery, remind students that there is no single correct answer for the arrangement of the elements. Remember that in Mendeleev’s first published table of the elements (1869), elements were listed in order of increasing atomic mass in columns, so that similar elements (e.g., Cl, Br, I) were found in horizontal rows rather than vertical columns. The vertical arrangement of similar elements into element groups appeared two years later, in 1871.
- Although Dmitri Mendeleev is often given top billing in textbook discussions of the development of the periodic table, Lothar Meyer in Germany is credited with independent discovery of the periodic law. In an 1870 paper, Meyer printed a graph of atomic volume versus atomic weight that revealed the characteristic repeating pattern in the properties of elements. In the same paper, Meyer also displayed an arrangement of the elements into a table of rows and columns on the basis of increasing atomic weight. Meyer did not, however, predict the existence of missing or undiscovered elements.
Correlation to Next Generation Science Standards (NGSS)†
Science & Engineering Practices
Developing and using models
Planning and carrying out investigations
Analyzing and interpreting data
Disciplinary Core Ideas
MS-PS1.A: Structure and Properties of Matter
HS-PS1.A: Structure and Properties of Matter
Systems and system models
HS-PS1-1. Use the periodic table as a model to predict the relative properties of elements based on the patterns of electrons in the outermost energy level of atoms.
Answers to Prelab Questions
- Ionization energy—Energy needed to remove one of the electrons from an atom (specifically, from an isolated atom in the gas phase). The energy needed to remove successive electrons is called the first ionization energy, second ionization energy, etc. Units are kilojoules per mole (kJ/mole).
- Atomic radius—For a neutral atom, the distance from the center of an atom’s nucleus to its outermost electron. Since the electron cloud that surrounds the nucleus does not have an exact boundary, the atomic radius of an atom is not a precise number. The atomic radius is usually estimated as one-half the distance between two atoms in a form of the element—for example, one-half the distance between chlorine atoms in the diatomic chlorine molecule. Units are nanometers (1 nm = 1 x 10–9 m).
- Density—The ratio of mass to unit volume for the standard form of the element. Units are grams per cubic centimeter (g/cm3) for a solid or liquid and grams per liter (g/L) for a gas. Density depends on temperature.
- Electronegativity—Assigned numerical value for an element that reflects the ability of an atom to attract electron density in a covalent bond. Electronegativity is not an amount of energy, nor can it be directly measured. There are no units for electronegativity; it is assigned on a relative scale from 0.5 to 4.0.
- Atomic mass—Also called the average atomic mass; the average mass of an element’s atoms. Since the mass of an individual atom is too small to be directly measured, atomic mass is defined relative to that of a reference atom, an arbitrary standard. Thus, the mass of the carbon-12 isotope is defined as exactly equal to 12 atomic mass units. The atomic mass of a particular atom is very nearly, but not exactly, equal to its mass number (number of protons and neutrons). The average atomic mass of an element is computed as a weighted average of the masses of the isotopes that make up the element and their fractional (natural) abundance. The units of atomic mass are atomic mass units (amu).
- Melting point—Temperature at which the solid form of an element is in equilibrium with the liquid phase at atmospheric pressure. Usually given in units of kelvin (K).
“Vertical” Table of the Elements
“Horizontal” Table of the Elements
Properties of the Missing Element
These are the predicted, not actual, properties. Student predictions will, of course, vary.
Answers to Questions
- Mendeleev’s Periodic Law can be stated: “The physical and chemical properties of elements are periodic functions of their atomic masses.” Looking at your arrangement of the element cards, describe in your own words what the term “periodic function” means.
“Periodic function” means that the properties of the elements repeat in a regular manner (are periodic) and that the cycle for the repeating pattern depends on (is a function of) the atomic masses of the elements.
- Some of the properties listed on each card are periodic properties, others are not. Name one property that is periodic and one that is not.
Ionization energy, electronegativity and atomic radius reveal distinct periodic trends when the elements are arranged in order of increasing atomic mass. Density and melting point show trends, but they are not as obvious. Atomic mass is not a periodic property.
- The elements in the modern periodic table are arranged in order of increasing atomic number (instead of increasing atomic mass). Why didn’t Mendeleev use atomic number to arrange the elements?
The concept of atomic number did not exist at the time of Mendeleev. Note: In 1913, the English chemist Henry Moseley, working in Ernest Rutherford’s laboratory on the properties of the nucleus, hypothesized that every element had a different amount of positive charge and that the amount of positive charge occurred in whole-number increments. Moseley introduced the concept of atomic number to account for the positive charge of the nucleus.
- From your instructor, obtain a handout showing one possible arrangement of the element cards. Identify each elements on the handout with its atomic number and chemical symbol. Use your textbook to obtain this information.
The elements are listed in order from left to right on the Teacher PDF, in rows according to their periodic number. The transition metals are not included. The atomic numbers of the elements listed are 3–20, 31–38 and 49–54.
- Using the possible arrangement of the element cards obtained from your instructor, pick two of the numerical properties of the elements that are periodic and plot their values on the graphs below. Give each graph a descriptive title and label the axes.
- There are certain trends in the properties of the elements, both within a column (from top to bottom) and across a row (from left to right) in the periodic table. On the arrow for each property, write the word increases or decreases to describe how that property changes.
- On the outline of the periodic table shown, locate the following: metals, nonmetals and metalloids (or semimetals).
- On the outline of the periodic table shown below, locate the following: groups or families of elements, periods or series of elements, noble gases, alkali metals, alkaline earth metals and halogens.
- On the outline of the Periodic Table shown, locate the following: transition elements, inner transition elements, representative elements.