Name: __________________________
Date: __________
Period: ______
Phases of Elements in the Periodic Table
Matter exists in nature as pure substances; elements and compounds, or in
mixtures. Each form of matter will be found in its’ natural phase of state at standard
temperature. Room temperature in Celsius is 25°C and in Kelvin it is 298 K. What is
the standard temperature in Kelvin AND degrees Celsius? [Hint: Standard
temperature exists at STP- Standard Temperature and Pressure]
K= 273

°C= 0  Found in Reference Table A
If a substance melts and boils at a temperature higher than standard
temperature then it’s phase is a solid.
Example: Sodium (Na) has a melting point (MP) of 371 K and a boiling
point (BP) of 1156K. Both are higher than standard temperature (273 K)
and therefore Na is a solid at room temperature because it has not yet
melted or boiled.

If a substances melts at a temperature lower than standard temperature
and boils at a temperature higher than standard temperature then it’s phase
is a liquid.
Example: Mercury (Hg) has a MP of 234 K and a BP of 630. K and
therefore it exists normally as a liquid at standard temperature (273K)
because it has melted but not yet boiled.

If a substance both melts and boils at a temperature below the standard
temperature, it exists as a gas.
Example: Oxygen (O2) has a MP of 54K and a BP of 90 K. Both are
lower than standard temperature (273 K) and therefore Oxygen exists
as a gas because it has already melted then boiled.
Your task is to analyze the melting point and boiling point for the selected elements in the
table below using Table S of the Reference Tables. Indicate whether each is below or above
standard temperature. Using this information indicate what phase the element exists in at
standard temperature (s, l, or g). Hydrogen has been done for you as an example.
Atomic #
Symbol
Name
Melting Point (K)
Boiling Point (K)
Phase
1
H
Hydrogen
14
20
gas
2
He
HELIUM
___
4
GAS
6
C
CARBON
___
___
SOLID
7
N
NITROGEN
63
77
GAS
8
O
OXYGEN
54
90
GAS
9
F
FLUORINE
53
85
GAS
10
Ne
NEON
24
27
GAS
17
Cl
CHLORINE
172
239
GAS
18
Ar
ARGON
84
87
GAS
26
Fe
IRON
1811
3134
SOLID
29
Cu
COPPER
1358
2835
SOLID
35
Br
BROMINE
266
332
LIQUID
36
Kr
KRYPTON
116
120
GAS
53
I
IODINE
387
457
SOLID
54
Xe
XENON
161
165
GAS
80
Hg
MERCURY
234
630
LIQUID
86
Rn
RADON
202
211
GAS
1. Which elements are liquids at room temperature?
2. Which elements are gases at room temperature?
3. Which elements are solid at room temperature?