Lesson4 Molecular Structure

SCIENCE
Grade 7

—SOMEONE FAMOUS

“You are never too old to set another

goal or dream a new dream.”

Unit 3 – Understanding matter

Module - Classification and states

of matter

Molecular Structure

Lesson 4

Learning Objectives

•

•

Vocabulary

✓ Molecular Structure
✓Elements
✓ Molecules
✓ Thermal energy
✓ Compounds
✓ Ionic compounds
✓Covalent compounds

✓ Polar covalent

compounds

✓ Graphite
✓ Amorphous carbon
✓ Diamond
✓ Melting point
✓Boiling point

Textbook # 73

Starter Activity

Which statement best describes what happened to the sugar?

Motohiro felt chilled by the rainy afternoon. He decided to
make a cup of hot tea. He let the tea leaves steep too
long and the tea was bitter. Motohiro added some sugar
to his tea to improve the flavor. After he stirred the sugar
with the tea, he couldn’t see the sugar any longer.

Activity – Agree/disagree

All substances dissolve in water.

In-class Activity - Discussion

Textbook # 75

Add a spoonful of sugar to one cup of water. Add
a spoonful of oil to a second cup of water. Stir each
cup. Record your observations

Activity - Discussion

Textbook # 75

Activity - Investigation

Textbook # 78

Elements

Textbook # 97

https://www.youtube.com/watch?v=qciaoQhOFz8

How do elements differ?

➢ An element is a substance that is made of only

one type of atom.

➢ Each element has a unique name that can be

found on the periodic table of elements.

➢ There are 118 known elements, and they are

listed on the periodic table.

➢ Elements have a wide range of properties.

➢ Most are solids at room temperature, but many

are gases, and some are liquids.

How are elements similar? How are they different? Let’s find out!

How do elements differ?

➢ While elements are made of individual atoms, there is more than one type of

structure for the atoms.

➢ There are three types of elemental structure.

Individual atoms

✓ Single atom, in which atoms are not

bonded to each other. Examples include
helium (He), neon (Ne), krypton (Kr).

Molecules

✓ Molecular, in which atoms are bonded to

one or more other atoms. Examples
include nitrogen (N2), oxygen (O2),
hydrogen (H2), and sulfur (S8).

How do elements differ?

Extended Structure

✓ Metallic, in which atoms are arranged in a regular

array and held together with non-directional bonds.
Examples include copper (Cu) and gold (Au).

✓ Network, in which atoms of the same type are

bonded in a continuous network, like one giant
molecule. Examples include carbon (diamond) and
silicon (Si).

Multiple Choice

True of False: Most of the Elements in the Periodic Table are metals.

• True

• False

Multiple Choice

What does the term 'conductor of electricity' mean?

• Causes the substance to heat up or cool down very quickly

• Causes the substance to heat up or cool down very slowly

• Can allow an electric current to flow through it

• Cannot allow an electric current to flow through it

Multiple Choice

What does the term 'malleable' mean?

• The substance can be drawn into wires

• The substance will break or fracture if a large force is applied (such as hammering)

• The substance has no effect if pressed or hammered

• The substance can be hammered or pressed into a shape without it breaking

Multiple Choice

What does the term 'brittle' mean?

• The substance can be drawn into wires

• The substance will break or fracture if a large force is applied (such as hammering)

• The substance has no effect if pressed or hammered

• The substance can be hammered or pressed into a shape without it breaking

Activity - LAB

Textbook # 80

Activity - LAB

Textbook # 80

Watch the experiment and answer the questions

Activity - LAB

Textbook # 81

Data and Observations

Element

Appearance
Shiny/dull

Hardness
Malleable/

brittle

Electrical

Conductivity

Yes/No

Sulfur

Iron nail

Aluminum foil

Charcoal

Copper

Activity - Investigation

Textbook # 81

Analyze and Conclude

6. Identify any patterns you observe between the substances.

7. Group the elements into categories with similar properties. Explain

your groupings.

Activity - Investigation

Textbook # 81

Analyze and Conclude

6. Identify any patterns you observe between the substances.

Shiny elements conduct electricity and dull elements do
not.

7. Group the elements into categories with similar properties. Explain

your groupings.

How do elements differ?

Properties of Metals and Nonmetals

❖ Elements can be classified into groups based on their structures and

properties.

❖ Elements are classified as metals or nonmetals based on their properties.

❖ Metals are on the left side of the periodic table and nonmetals are on the

right side.

How do elements differ?

Type of
element

Characteristic Properties

Metals

•shiny appearance

•malleable and ductile (able to be hammered into sheets and drawn into wires)

•most are solid at room temperature (except mercury, which is a liquid)

•good conductors of electricity and thermal energy

Nonmetals

•dull appearance

•brittle (break or shatter when hammered)

•about half are solid at room temperature and pressure, about half are gases, and
one (bromine) is a liquid

•poor conductors of electricity and thermal energy

Compete Alef

69

check my

understanding

Multiple Select

What are the common properties of metals?

• They are good conductors of heat and electricity

• They are brittle

• They are poor conductors of heat and electricity

• They are malleable

• They are shiny

Multiple Select

What are the common properties of non-metals?

• They are good conductors of heat and electricity

• They are poor conductors of heat and electricity

• They are brittle

• They are malleable

• What are the common properties of non-metals?

Question time:

➢
Sample A is shiny and can be hammered into a sheet. Sample B is
dull and brittle.

➢
What kinds of elements are these?

➢ What other test could you conduct to add evidence for your

classification?