Name: _______________________________________ Block: ____________ Date: _____________
LCPS Core Experience | Atomic Structure Investigation ONE
Atomic Structure
Stu de nt No tes
OBJECTIVES
Students will:
 identify the chemical and physical properties of unknown elements.
 use chemical and physical properties of elements to classify them as metals,
nonmetals and metalloids.
 use collected data to classify the unknown elements as a metal, non-metal, or
metalloid.
LINK
1. What makes each element different?
Each element is different because its ____________ and chemical properties are different.
2. How are elements similar?
Each element is similar because it is in its ____________form and they each have unique
properties.
Lesson One: Identifying Elements Using Physical and Chemical Properties
Background
All of the 118 elements can be grouped into one of three categories. An element is either a
metal, a nonmetal or a metalloid. Elements are grouped into the three categories based on
differences in their different properties. The physical and chemical properties of the metals,
nonmetals and metalloids are all very different. Physical properties include appearance and
hardness. Chemical properties include an element’s reactivity with other chemicals.
Clues of reactivity include (1) gas formation (bubbling), (2) solid formation (precipitate), (3)
color change, and/or (4) a change in energy (exothermic or endothermic). Reactions may
display more than one of these chemical reaction clues.
All physical and chemical properties depend upon the differences in the atomic structure of
each of the elements. Atomic structure includes the number of electrons orbiting the nucleus
and the number of protons and neutrons found in an element’s nucleus.
EXPERIMENT
Lesson One: Identifying Elements Using Physical Properties
1. In this investigation you will investigate elements from different categories of the Periodic
Table. The three main categories of the Periodic Table are: metals, metalloids and nonmetals.
2. You will investigate the physical and chemical properties of four unknown elements.
Samples of the four elements are provided. Remember that elements in the same category
share similar physical and chemical properties as described in Table A.
Atomic Structure Investigation ONE
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LCPS Core Experience | Atomic Structure Investigation ONE
Table A: Physical and Chemical Properties of Elements
Physical Properties
Metals


metals often have a lustrous or shiny appearance
metals are often hard and malleable
Nonmetals


nonmetals are often dull in appearance
nonmetals are often soft and brittle
Metalloids


metalloids can have an appearance that is either shiny or dull
metalloids can be either soft or hard, malleable or brittle
Chemical Properties
Metals


most metals react with a solution of silver nitrate (AgNO3)
most metals react with hydrochloric acid (HCl)
Nonmetals


most nonmetals do not react with a solution of silver nitrate (AgNO3)
most nonmetals do not react with hydrochloric acid (HCl)
 most metalloids do not react with a solution of silver nitrate (AgNO3)
 most metalloids do not react with hydrochloric acid (HCl)
a. Based on the information in Table A, what questions could you ask about the properties
of your samples that would help you identify them? Write your questions below.
________________________________________________________________________
Metalloids
________________________________________________________________________
________________________________________________________________________
b. Review and use the information in Table A as you conduct your investigation to help
you classify each sample, as a metal, a nonmetal or a metalloid.
3. Obtain the unknown elements from the distribution station. The unknown samples are labeled
A, B, C, and D. Place one scoopula of each sample in the appropriately labeled weigh dish.
Begin by observing the physical properties of the samples.
a. Judge the appearance of each element and determine if it is shiny or dull.
b. Use a scoopula to judge whether each element is hard or soft.
c. Record and organize your observations in the Table B.
Atomic Structure Investigation ONE
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LCPS Core Experience | Atomic Structure Investigation ONE
4. Continue your investigation by observing the chemical properties of the unknown samples by
determining whether each reacts with solutions of silver nitrate (AgNO3) and hydrochloric acid
(HCl). For this part of the experiment you will use only one form of each element.
a. Make sure you have two sets of test tubes labeled A, B, C, and D. Separate your test
tubes into two sets. Place one set in one test tube rack labeled AgNO3. Place the second
set in the rack labeled HCl. Add one dropper full of silver nitrate (AgNO3) solution to
the set of test tubes in the AgNO3 rack. Keep all test tubes in the test tube rack when
adding chemicals.
b. If the sample is a solid, add one piece to its labeled test tube. If the sample is a powder,
fill the tip of the scoopula with the sample and add it to its labeled test tube.
c. Record any signs of chemical reactions in Table B. If no reaction is visible, write No
Reaction.
d. Add one dropper full of hydrochloric acid (HCl) solution to each test tube in the rack
labeled HCl. Keep all test tubes in the test tube rack when adding chemicals. Add
each sample to its labeled test tube. Record any signs of chemical reactions in Table
B. If no reaction is visible, write No Reaction.
Table B: Properties of Unknown Elements
Physical Properties
Element
Appearance
Hardness
Chemical Properties
Reaction with
Reaction with
AgNO3
HCl
A
B
C
D
5. Discuss the results of your investigation with other members of your group.
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LCPS Core Experience | Atomic Structure Investigation ONE
6. Dispose of the solutions per teacher directions.
LEARNING REVIEW
List three things you have learned about metals, nonmetals, and metalloids or physical and
chemical properties from this investigation.
a. Each classification; metals, nonmetals and metalloids share similar __________ and
physical properties, which help to identify them.
b. In order to observe a chemical property a chemical reaction must occur.
c. Physical properties are properties that you can _____ without changing the substance.
EVALUATION
1. Based on your data and discussions, classify each sample as a metal, a nonmetal or a metalloid.
Use Table C to make your classifications.
Table C: Classification of Unknown Elements
Element
Metal
Metalloid
Nonmetal
A
B
C
D
2. Explain why you classified each element as a metal, a nonmetal or a metalloid. What data did
you have to support your conclusions?
Substances A, and B were classified as ________ because one of the physical forms of each was shiny,
hard and reacted with the silver nitrate (AgNO3) solution and hydrochloric acid (HCl).
Substance C was classified as a _____________ because it was shiny, hard and did not react with the
silver nitrate (AgNO3) solution and hydrochloric acid (HCl). Although its physical properties were
also similar to metals, its lack of reactivity was more consistent with the property of a metalloid.
Substance D was classified a _______________ because the physical form was dull, soft and did not
react with the silver nitrate (AgNO3) solution or hydrochloric acid (HCl). Although both nonmetals
and metalloids may be dull in appearance and unreactive with AgNO3 and HCl, sample D was
relatively soft, a property more closely associated with nonmetals than metalloids
Your teacher should review numbers 1 & 2 before you answer the remaining questions.
3. Obtain the identity of each unknown sample from your teacher and record the identity of
each element in Table D.
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LCPS Core Experience | Atomic Structure Investigation ONE
Table D: Identity of Unknown Elements
Element
Identity
A
B
C
D
Category
a. Do the identities of the elements match your results? Which are different and which are
the same?
________________________________________________________________________
b. If the identities of the elements, do not match your results, which of physical property
or chemical property made you misidentify the sample?
________________________________________________________________________
4. How are elements that are metals, metalloids and nonmetals different? How are they similar?
Metals are ________and usually shiny but nonmetals are usually soft and _______ in
appearance. Metalloids can be either hard or soft and either shiny or dull. Metals usually
_________ with silver nitrate and hydrochloric acid but nonmetals and metalloids do not
react with either compound.
5. A chemist found a sample of an element in his prep room. He ran some tests to identify the
unknown sample. Its physical properties included being soft, black and shiny. Chemically, it
did not react with HCl, but there were slight bubbles with AgNO3. What is the possible class
of this unknown element on the Periodic Table. Is the unknown a metal, non-metal or
metalloid?
The unknown is a ___________________.
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