1. The Modern Periodic Table
5.2 Reading Guide

2. 9. How is a keyboard an example of a periodic pattern?
On a keyboard there is a repeating pattern of notes. The scale repeats at regular 8-note intervals.

3. 10. How are elements arranged in the modern periodic table?
In the modern periodic table the elements are arranged by increasing atomic number.

4. 11. Why didn’t Mendeleev arrange the elements like they are in the modern periodic table?
Mendeleev developed his periodic table before the discovery of protons. He didn’t know that each element has a unique number of protons.

5. 12. Please describe what a “period” is on the periodic table.
Each row in the periodic table is called a period.

6. 13. According to the periodic table at the top of page 131, how many elements does period 7 have?
Period 7 has 32elements:
Spaces have been left for those that haven’t been discovered (synthesized)

7. 14. Why does the number of elements per period differ?
The number of elements per period varies because the number of available orbitals increases from energy level to energy level.

8. 15. Please explain what a “group” is on the periodic table.
Each column on the periodic table is called a group.

9. 16. What do elements in the same group have in common?
Elements within a group have similar properties.

10. 17. An element’s electron configuration determines its __________ properties.
Chemical
Chemical properties = reactivity & flammability

11. 18. Please explain the periodic law.
Periodic law refers to a pattern of repeating properties
Members of a group in the periodic table have similar properties.

12. 19. Look at page 132-133. What is the first element in group 2A?
Be = Beryllium

13. 20. What is the definition of an atomic mass unit (amu)?
An amu is defined as one twelth the mass of a carbon-12 atom

14. 21. Please explain what a weighted average is.
In a weighted average some values are more important than other values.
E.g. grades – 60% tests, 25% labs, 15% daily work

15. 22. How are weighted averages related to mass numbers (atomic mass)?
Atomic mass depends on the distribution of an elements isotopes in nature.
Those isotopes that occur in higher numbers naturally are given more “weight” in the average.
E.g. grades – test scores are weighted more heavily than labs

16. 23. What are 3 ways that the periodic table classifies elements?
Metals
Nonmetals
Metalloids

17. 24. What are 3 properties of metals?
Good conductors of electricity and heat
Malleable
Ductile

18. 25. What is one distinctive property of the transition elements?
The transition elements have the ability to form compounds with distinctive colors
E.g. colored glass
E.g. Black Hills gold

19. 26. What are 2 properties of non-metals?
Poor conductors of heat & electricity
Low boiling points so mostly gases at room T
If solid at room T then brittle

20. 27. What are metalloids?
Metalloids are elements with properties that are between those of metals and nonmetals
A metalloids ability to conduct electric current depends on T

21. 28. What happens to elements as you move from left to right across the periodic table?
Across a period from left to right, the elements become less metallic and more nonmetallic in their properties.