Unit 4 Chemistry Review

How many valence electrons do alkail metals have?

1

How many valence electrons do alkail earth metals have?

2

How many valence electrons do halogens have?

7

How many valence electrons do nobel gases have?

8

How is the modern periodic table arranged today? What patterns are observed in the arrangement of elements in the periodic table?

Increasing atomic number. Repeating properties every 8 elements.

Who rearranged the periodic table to a format that is similar to what is used today?

Mendeleev

How did he arrange the elements in his table?

Arranged in groups of similar properties

How is the modern periodic table arranged today?

Increasing atomic number.

What is a valence electron and why is it important to know how many valence electrons each element has?

Electrons found in the outermost energy level. Tells how reactive an element is.

What is meant by the term effective nuclear charge? How is it calculated?

Zeff (Z-S) [Number of protons - Core Elections]

How does the effective nuclear charge experienced by the valence electrons of an atom vary going from left to right across a period of the periodic table?

Zeff of Li=1+, so electron feels 1 proton pulling it in. F=7+, so electron feels 7 protons pulling it in.

Arrange these elements in order of increasing atomic size: aluminum, chlorine, sodium and sulfur. Does your arrangement demonstrate a periodic trend or a group trend?

chlorine, sulfur, aluminum, sodium. All elements of 3rd period.

Arrange these elements in order of decreasing ionization energy: beryllium, calcium, magnesium, stron tium. Does your arrangement demonstrate a periodic trend or a group trend?

beryllium, calcium, magnesium, strontium. Group trend.

Ionization energy measures the ease with which an atom _________ an electron, whereas electron affinity measures the ease with which an atom _________ an electron.

loses, gains

List 4 properties of metals

shiny, good conductor, bendy, left side of PT, mostly solids.

List 4 properties of nonmetals.

solid/liquid/gas, right side of PT, dull, britle, bad conductior.

List and explain at least 3 uses of radioactivity in the world.

Nuclear Power Plant: Creates Energy.

Medicine: Cancer treatment

Military: Nuclear Bombs (Hiroshima and Nagasaki)

What part of an atom undergoes change during radioactive decay? What can cause this instability?

Nucleus. ratio of Protons and Neutrons