The Periodic Table Flashcards
All 13 cards in this deck
How did Mendeleev arrange the elements in his periodic table?
In order of increasing relative atomic mass, grouping elements with similar properties (of the elements and their compounds) in the same column.
Why did Mendeleev leave gaps in his periodic table?
For elements that had not yet been discovered, so that elements with similar properties stayed in the same group.
How did Mendeleev predict the properties of undiscovered elements?
He used the properties of the neighbouring elements (and their compounds) around each gap.
Why did ordering by relative atomic mass sometimes put elements in the wrong place, so Mendeleev had to swap some pairs?
Because of the relative abundance of isotopes of some pairs of elements, the heavier element can have the smaller atomic number.
In what order are the elements arranged in the modern periodic table?
In order of increasing atomic number.
What are the rows and the vertical columns of the periodic table called, and what do elements in a column share?
Rows are periods; vertical columns are groups. Elements in the same group have similar properties.
Where are the metals and the non-metals found in the periodic table, and how do their atoms differ in reactions?
Metals on the left and centre, non-metals on the right. Metal atoms lose electrons to form positive ions; non-metal atoms gain (or share) electrons.
What are the steps to write the electronic configuration of one of the first 20 elements?
e.g. sodium, atomic number 11
- Number of electrons = atomic number: 11
- Fill shells 2, then 8, then 8: 2, 8, 1 left
- Write with dots between shells: 2.8.1
How many electrons can the first, second and third shells hold for the first 20 elements?
First shell 2, second shell 8, third shell 8 (then the fourth shell starts).
Explain, in terms of electrons, why two elements are in the same group of the periodic table.
They have the same number of electrons in their outer (electron) shell.
How is the period an element is in related to its electronic configuration?
The period number equals the number of shells holding electrons.
e.g. chlorine (2.8.7) has three occupied shells, so it is in period 3
How is the group number of an element in Groups 1–7 related to its electronic configuration, and what is different about Group 0?
In Groups 1–7, the group number is the number of electrons in the outer shell, e.g. oxygen (2.6) is in Group 6.
Group 0 doesn't follow this: its atoms already have a complete outer shell (two electrons in helium, eight in the others).
What evidence supported Mendeleev's periodic table after he published it?
Elements he had left gaps for were later discovered, and their properties closely matched his predictions.
e.g. gallium, which he had called eka-aluminium