Atom and Periodic Table Basics

The second energy level (orbital) of an atom can hold a maximum of how many electrons?

• 2

• 4

• 8

• 18

Which box has a higher density?  

• Box A

• Box B

• cannot be determined

• they are the same

Elements and compounds are always a ___.

• pure substance

• mixture

Each column in the periodic table is called a _________ .

• period

• group

• cluster

• unit

Groups on the periodic table are __________.

• Horizontal Rows

• Vertical Columns

Periods on the periodic table are __________.

• Horizontal Rows

• Vertical Columns

The periodic table is a chart that organizes the elements based on their atomic properties. Elements in the periodic table are organized according to the periodic law. The periodic law states that chemical and physical properties of elements are periodic functions of their atomic numbers (the number of protons in the nucleus). As the atomic number of elements increases, different elements display similar characteristics at regular intervals.

Periodic law states that elements are arranged _______________________________________________________________.

• in alphabetical order.

• from largest to smallest.

• as periodic functions of their atomic numbers.

• there is no rhyme or reason.

In 1869, Dmitri Mendeleev developed the first periodic table, organizing the elements according to atomic weight. When he ordered the elements, he noticed that there were patterns of repeating properties. The modern periodic table sequences elements from left to right by atomic number.

This was the first person to organize a periodic table.

• Neils Bohr

• Dmitri Mendeleev

• Democritus

• Ernest Rutherford

In the periodic table, similar elements are arranged in vertical columns called groups. Some of the major groups include Group 1: alkali metals; Group 2: alkaline earth metals; Group 17: halogens; and Group 18: noble gases. Elements within each group have similar properties and characteristic behaviors because of their similar numbers of valence electrons.

In what direction are groups arranged in the periodic table?

• Side to side

• Up and down.

• Diagonally

• In sections.

Elements in the same group or column have the same ...

• # of valence electrons

• # of shells

• # of protons

• Mass Number