Name: _______________________________________________________
Chapter 2 – Elements and the Periodic Table
Section 1 – Introduction to Elements Key Questions
 What is the structure of an atom?
1. Atoms are made up of _protons, ___neutrons_, and _____electrons_.
2. Atoms consist of _a nucleus_ and _one or more electrons_.
3. Protons:
Neutrons:
Electrons:
Found: nucleus
Found: nucleus Found: outside the nucleus in the cloud
Charge: _+_
Charge: none
Charge: _-__
 How are elements described in terms of their
atoms?
4. An element can be identified by the number of protons in the nucleus of its
atoms.
5. Every atom of an element has the same number of protons. Each element has a
unique atomic number.
6. Isotopes - Atoms with the same number of protons but different numbers of
neutrons. Isotopes are identified by its mass number or the sum of the
_protons_ and _neutrons__.
7. Although the atoms of an element may have different mass numbers, they
react the same chemically.
 Why are models useful for understanding atoms?
8. Atoms are _hard to study_ because they are _so small_.
9. Because atoms are so _tiny_, scientists create _models_ to describe them.
10. A model could be:
a diagram
a mathematical equation
a mental picture
an object
11. A model is used to study
events or objects that are
too large, too small, too fast, too slow, too far away
too dangerous
Section 2 – Organizing the Elements
 How did Mendeleev discover the pattern that lead to the Periodic Table?
12. Mendeleev wrote each element’s _melting point_, _density_, _color_, _atomic
mass, and _the number of chemical bonds_ it could form.
13. Atomic Mass_ - the average mass of all the isotopes of that element
14. Mendeleev noticed _a pattern_ of _properties_ appeared when he averaged
the elements in order of increasing atomic mass.
 What data about elements are found in the Periodic Table?
15. _Atomic Number_ - the number of protons
_Name_ and _Symbol_ - _Symbol_ contain either one or two letters
16. _Atomic Mass_ - average because most elements consist of a mixture of
_isotopes_.
 How is the organization of the Periodic Table useful
for predicting the properties of elements?
17. The _properties_ of an element can be predicted from its _location_ on the
Periodic Table.
18. _Periods_ - horizontal rows – elements decrease in _reactivity_ as you move
from left to right.
19. _Groups_ - vertical columns, also called _families_, most are named for the
_first_ element in the column.
Section 3 – Metals
 What are the physical properties of metals?
20. Chemists classify an element as a metal based on its _properties_.
21. Physical Properties
shininess
malleability
ductility
conductivity
definition
Reflective and smooth
Can be shaped
Can be drawn into wires
Can transfer heat and electricity easily
Chemical Properties
22. The ease and speed with which an element combines, or _reacts_, with other
elements and compounds is called _reactivity_.
23. Metals usually react by _losing _electrons_ to_ other_ elements_.
Examples:
24. Highly reactive metals - _sodium (Na)_
25. Unreactive metals - _gold (Au)_ and _platinum (Pt)_
26. The destruction of a metal due to reaction is called _corrosion_.
 How does the reactivity of metals change across the Periodic Table?
27. The reactivity of metals tends to _decrease_ as you move from left to right
across the Periodic Table.
28. Group 1 metals - lithium, sodium, potassium, rubidium and francium- are called
_Alkali Metals_.
29. These react by _losing_ _one_ _electron_.
30. Two most important Alkali Metals are _sodium (Na)_ and _potassium (K)_.
31. Group 2 metals – beryllium, magnesium, calcium, strontium, barium, and radon –
are called _Alkaline Earth Metals_.
32. These react by _losing_ _two_ _electrons_.
33. Two most common Alkaline Earth Metals are _magnesium (Mg)_ and _calcium
(Ca)_.
34. Groups 3-12 are called _Transition metals_. Most are _hard_, shiny_ and
_good conductors_.
35. Metals in groups 13-15 are not nearly as _reactive_ as those on the left side
of the table.
36. _Lanthanides_ and _Actinides_ - two rows of elements are placed below the
main part of the periodic table.
37. A(n) _alloy_ is a mixture of a metal with at least one other element, usually a
_another metal_.
 How are elements that follow uranium in the Periodic Table produced?
38. Elements with atomic numbers higher than 92 are described as _synthetic_
because they are not found naturally on Earth.
39. These are made – or _synthesized_ - when nuclear particles are forced to
crash into one another.
40. _Particle Accelerators_ move atomic nuclei faster and faster until they have
reached very high speeds and cause the particles to combine.
Section 4 – Nonmetals and Metalloids
 What are the properties of nonmetals?
42. Life on Earth depends on _nonmetals_. All organisms are made from _carbon_.
43. A _nonmetal_ is an element that lacks most of the properties of a metal.
44. Most are _poor conductors and are reactive_ with other elements. Solid
nonmetals are _dull_ and _brittle_.
Physical properties
45. Most are gases_at room temperature except bromine_ which is a liquid at
room temperature.
46. Most have properties that are opposite_ to metals. Most have _lower_
densities than metals.
Chemical properties
47. Most are reactive_so they readily form compounds.
48. Fluorine_ is the most reactive nonmetal.
49. _Group 18 elements_ hardly ever form compounds.
50. Atoms of nonmetal usually _gain_ or _share_ electrons when they react with
other atoms.
51. Many nonmetals can form compounds with other nonmetals to create a(n)
_molecules_.
52. The _Carbon_ family, or group _14_ has atoms that can _gain_, _lose_, or
_share_ four electrons when reacting with other elements.
53. The _Nitrogen_ family, or group _15_ contains two nonmetals, _nitrogen_ and
_phosphorus_.
54. _Nitrogen_ is an example of an element that occurs in nature in the form of
__diatomic molecule_ meaning it consists of two atoms.
55. _Phosphorus_ is much more reactive than nitrogen, so it is only found in
nature in as a compound.
56. The _Oxygen_ family, or _Group 16_ contains three nonmetals, _oxygen_,
_sulfur_, and _selenium_. These usually _gain_ or _share_ two electrons when
reacting with other elements. Like nitrogen, _oxygen_ is also a diatomic molecule.
It can also form a triatomic molecule called _ozone_.
57. Because oxygen is _highly reactive_, it can combine with almost every other
element. It is the _most abundant element_ in the Earth’s crust and _secondmost abundant_ in the atmosphere.
58. The _Halogen_ family, or group _17_ contains _fluorine_, _chlorine_,
_bromine_, _iodine_, and _astatine_.
59. Halogen means _salt-forming_.
60. Halogen atoms usually gain or share _one_ electron when it reacts with other
elements.
61. All halogens are _very reactive_, and the _uncombined elemental_ form is
dangerous to humans.
62. The _Noble_ gases, or group _18_ do not normally form compounds because
their atoms do not usually _lose_, _gain_ or _share_ electrons. Therefore they
are _usually unreactive (stable)_.
63. _Hydrogen_ is the simplest and smallest atom. It cannot be grouped into any
family because the chemical properties differ very much from all other families
or groups_.
 How are the metalloids useful?
64. Along the border between the metals and nonmetals are _7_ elements called
_metalloids_.
65. They have _some_ characteristics of both metals and nonmetals. _Most_are
solid at room temperature, _brittle_, _hard_, and somewhat _reactive_.
66. Most common metalloid - _silicon_
67. The most useful property of the metalloids is _their_ _varying_ _ability_
_to_ _conduct_ _heat and electricity_ which makes the semiconductors.
68. _Semiconductors_ are substances that can conduct electricity under some
circumstances but not under other conditions. We use them to make _computer
chip_, _transistors_ and _lasers_.