Catalyst – pick up a periodic table before starting class

1. Compare the number of protons in elements going from left to right across the period 4 and group 18:

Choose two elements to compare What are their atomic numbers?

2. Compare the atomic mass in elements going from left to right across period 4 and group 18:

Choose two elements to compare What are their atomic mass numbers?

Look at your periodic table to identify patterns. 3. The atomic number of elements in the periodic table (increases/decreases) as you move from right to left across a period and (increases/decreases) as you move from top to bottom down a group.4. The atomic mass of elements in the periodic table (increases/decreases) as you move from right to left across a period and (increases/decreases) as you move from top to bottom down a group.

Homework

Complete the study guide!STUDY! STUDY! STUDY! You can even

use your periodic table study guide to help you!

What will be on tomorrow’s quiz? Groups, periods Metals, metalloids, and non-metals Trends in the Periodic Table

How are you going to see it on the TCAP and on your assessment?

You should be able to recognize the trends in the periodic table without seeing the atomic numbers and atomic masses

This means you need to be able to recognize what happens as you move from left to right across a period in the periodic table and as you move from top to bottom down a group on the periodic table

As you compare elements from left to right across the periodic table, you will notice a trend or regular change in a number of properties. The same thing happens if you go up and down on the periodic table and compare the properties of the elements.

You need to know the trend for: # of protons # of electrons # of neutrons Atomic number Atomic mass

Make sure you recognize if the trend is increasing or decreasing as you move across a period (row)

Make sure you recognize if the trend is increasing or decreasing as you move down a group (column)

Atomic Number

The periodic table is organized in order of increasing atomic number! Therefore, atomic number will increase as you move from left to right across a period and as you move from top to bottom down a group.

We also know that the atomic number is exactly equal to the number of protons so the trend for protons will be the same

In a neutral atom, the number of protons equals the number of electrons, so the trend for electrons will be the same as well

Increases

Increase

TREND IN ATOMIC NUMBER

Increases

Increase

TREND IN # of PROTONS

Increases

Increase

TREND IN # OF ELECTRONS

Trend in Atomic Mass

Atomic mass is equal to the number of protons plus the number of neutrons in the atom of an element

We can think of atomic mass of how heavy a substance is

Since the number of protons is increasing across and down the periodic table, the atomic mass increases the same as atomic number

Therefore, elements get heavier as you move from left to right across a period and as you move from top to bottom down a group

Increases

Increase

TREND IN ATOMIC MASS

Trend in Neutrons

# of neutrons = atomic mass – atomic #

As a result of the atomic mass and atomic number increases, the number of neutrons will generally increase as well as you move across a period from left to right and as you move down a group

Increases

Increase

TREND IN # OF NEUTRONS

☐ Draw the trends we went over in class (show how these increase/decrease from right to left across a period and increase/decrease from top to bottom down a group):

☐Atomic number☐# of protons☐# of electrons

☐Atomic mass number☐# of neutrons

☐ Create a key to help you calculate “atomic math” ☐ How do you calculate the # of protons? ☐ How do you calculate the # of electrons? ☐ How do you calculate the # of neutrons?

☐ Write a minimum of one complete sentence including an explanation explaining each of the trends. (Ex: The number of protons increases in the elements of the periodic table as you move from left to right across a period and top to bottom as you move down a group because the atomic number increases and the atomic number represent the number of protons in the atom of an element.☐Atomic number

☐# of protons☐# of electrons☐Atomic mass number☐# of neutrons

Brain Teaser

Solve the puzzle- what element is this?

Find the number of electrons for this element

Find the atomic number for this element