The Periodic Table Flashcards

All 17 cards in this deck

How did Mendeleev arrange the elements in his periodic table?

In order of increasing relative atomic mass, placing elements with similar properties (of the elements and their compounds) in the same vertical column.

Why did Mendeleev leave gaps in his periodic table?

For elements not yet discovered, so that elements with similar properties stayed in the same group.

What did Mendeleev use the gaps in his table to do?

Predict the existence and the properties of elements not then discovered, using the properties of neighbouring elements.

Why is ordering elements by relative atomic mass not always the same as the modern order?

Because the relative abundance of isotopes makes some elements have a higher relative atomic mass than the element that follows them.
e.g. argon (40) comes before potassium (39)

True or false? Mendeleev arranged his table in order of atomic number.

False. Protons and atomic number were not known then, so he used relative atomic mass.

What is the atomic number of an element?

The number of protons in the nucleus of one of its atoms; it gives the element its position in the periodic table.

In what order are the elements arranged in the modern periodic table?

In order of increasing atomic number (proton number).

What are the rows and the vertical columns of the periodic table called?

Rows are periods; vertical columns are groups.

Why does potassium appear after argon in the periodic table, even though argon has the greater relative atomic mass?

The periodic table is in atomic number order: argon has 18 protons and potassium has 19.

Where are the metals and the non-metals found in the periodic table?

Metals on the left and in the centre; non-metals at the top right (plus hydrogen).

How does atomic structure explain the division between metals and non-metals?

Metal atoms have few electrons in their outer shell and lose them to form positive ions; non-metal atoms have nearly full outer shells and gain or share electrons.

True or false? Elements in the same group of the periodic table have similar chemical properties.

True. They have the same number of electrons in their outer shell.

How many electrons fill the first, second and third shells for the first 20 elements?

First shell 2, second shell 8, third shell 8 (then the fourth shell starts).

What are the steps to write the electronic configuration of one of the first 20 elements?
e.g. sodium, atomic number 11

1. Number of electrons = atomic number: 11
2. Fill the first shell with 2: 2
3. Fill the next shells (8, then 8) until all electrons are used: 2.8.1

What are the steps to draw the electronic configuration of an atom as a shell diagram?
e.g. oxygen, atomic number 8

1. Draw the nucleus and label it with the symbol: O
2. Add a circle (shell) and put 2 electrons on it: 2
3. Add further shells, up to 8 electrons each, until all are drawn: 6 on the second shell (2.6)

True or false? An atom with the electronic configuration 2.8.3 is in group 3 and period 3.

True. 3 outer electrons gives group 3; 3 occupied shells gives period 3.

True or false? Group 0 elements have no electrons in their outer shell.

False. They have a full outer shell — 8 electrons (helium has 2).