The Periodic Table Flashcards
All 11 cards in this deck
How did Mendeleev arrange the elements in his periodic table?
In order of increasing relative atomic mass, grouping together elements with similar properties of the elements and their compounds.
Why did Mendeleev leave gaps in his periodic table?
For elements that had not yet been discovered, so that the known elements lined up with others of similar properties.
How did Mendeleev predict the properties of elements that had not yet been discovered?
He used the trend/pattern in the elements around the gap (above and below in the same group, left and right in the period), taking a value between the surrounding elements.
Why was Mendeleev's ordering by increasing relative atomic mass not always true?
Because of the relative abundance of the isotopes of some elements: in a few pairs, such as tellurium and iodine, the element that belongs first has the higher relative atomic mass.
What is the atomic number of an element?
The number of protons in the nucleus of its atoms; elements are placed in the periodic table in order of increasing atomic number.
True or false? Elements in the same period of the periodic table have similar chemical properties.
False. Elements with similar properties are in the same group (vertical column); a period is a horizontal row.
How can you tell from its position in the periodic table that an element is a metal?
It is on the left-hand side or in the middle of the table; its atoms lose outer electrons to form positive ions.
e.g. calcium is in group 2, so it is a metal.
What are the steps to write the electronic configuration of one of the first 20 elements?
e.g. calcium (atomic number 20)
- Number of electrons = atomic number: 20.
- Fill the shells in order, up to 2, then 8, then 8: 2.8.8.
- Put the remaining electrons in the next shell: 2.8.8.2.
How does an element's electronic configuration tell you its period?
e.g. chlorine, 2.8.7
The number of shells (numbers in the configuration) is the period number: chlorine has 3 shells, so it is in period 3.
True or false? Potassium and caesium are in the same group because they have the same number of electron shells.
False. They are in the same group because they have the same number of electrons (1) in their outer shell.
How does an element's electronic configuration tell you its group?
e.g. chlorine, 2.8.7
For groups 1 to 7, the number of electrons in the outer shell is the group number: chlorine has 7, so it is in group 7. Group 0 elements have a full outer shell.