Counting Elements and Compounds

The Foundations of Matter

6th Grade

Elements and Compounds

• Elements are pure substances.

• Compounds contain a combination of elements in order to make them up. They are made of at least two types of matter.

Each element on the Periodic Table can be broken down like this. The atomic weight is also called the atomic mass and the element symbol is also called the chemical symbol.

Elements and Compounds

Since compounds contain multiple elements, you can tell which and how many elements are in a compound by checking for the element symbols. For example, H2O contains 2 elements: Hydrogen (H) and Oxygen (O). A good rule to remember when counting elements in a compound is to count the capital letters. Each time you see a capital letter, then that starts a new element symbol. REMEMBER, COMPOUNDS ARE REPRESENTED BY A CHEMICAL FORMULA WHILE ELEMENTS ARE REPRESENTED BY A CHEMICAL SYMBOL.

Atoms

• An atom is the smallest particle of any type of matter.

• Atoms make up elements and elements make up compounds.

Multiple Choice

Elements and compounds are related however, they are different. Unlike elements, compounds...

• consists of only one type of atom

• are the smallest form of a particle

• exist only as pure substances

• are made of at least two types of matter

Multiple Choice

Using this picture, "Na" is called the element's...

• formula

• name

• symbol

• compound

Multiple Choice

Look at the given compound. Be3Al2(SiO3)6. How many different elements are in the compound?

• 4

• 5

• 3

• 7

Multiple Choice

The chart lists some substances and their symbols. How many of these substances are an example of an element?

• 1

• 2

• 3

• 4

Multiple Choice

How are elements and compounds different?

• A compound is represented by a chemical formula, and elements are represented by a chemical symbol.

• Compounds are represented by chemical symbols of one letter, and elements are represented by symbols of two letters.

• Elements are pure substances, and compounds are not.

• Elements are always larger units of matter, and compounds are smaller.

Multiple Choice

Using the image, what is the chemical symbol for magnesium?

• 12

• Mg

• Magnesium

• 24.31

Multiple Choice

The smallest particle of any particle type of matter is known by which of the following terms?

• Element

• Chemical

• Atom

• Compound

Open Ended

Describe the main difference between an element and a compound. Be sure to include the following ideas: pure substances and combinations.

Chemical and Physical Change

• A chemical change is when a substance becomes an entirely new substance.

• A physical change only changes the appearance of a substance, not its chemical composition.

• Examples of chemical changes include temperature change, something burning, something rotting, or a precipitate forming (when two liquids are mixed, and a solid substance forms)

• Examples of a physical change include cutting, melting, boiling, etc.

Multiple Choice

Which of the following situations provides evidence that a chemical change has taken place?

• Water, when boiled, evaporates and turns into vapor.

• Sugar, when added to iced tea, dissolves into the liquid.

• Two liquids are mixed, and a solid substance forms.

• A piece of paper is cut into many small pieces.

Multiple Choice

When two substances are mixed, they might form a new substance. Which of the following would indicate that a new substance has been formed?

• The temperature of the mixture decreases

• The volume of the mixture increases

• The mass of the mixture increases

• One of the substances dissolves

Density

Density is a measurement that compares the amount of matter an object has to its volume. We calculate density by using the formula D=M/V or density equals mass divided by volume.

Example: An object has a mass of 20 g and a volume of 2 cm3. Our formula would be 20g/2cm3= 10g/cm3. We divided 2 into 20 which gave us 10.

Multiple Choice

A balance and a graduated cylinder are used to determine the density of a mineral sample. The sample has a mass of 14.7 g and a volume of 2.2 cm3. What is the density of the mineral sample?

• 0.15 g/cm3

• 32 g/cm3

• 13 g/cm3

• 6.7 g/cm3

Element Properties

• Elements are grouped into categories based on their common properties.

• The three major categories are metals, nonmetals, and metalloids.

• Metals are elements that are shiny (luster), good thermal and electrical conductors, malleable (can be extended or shaped by beating with hammer or by the pressure of rollers), and ductile (able to be drawn out into thin wire).

• Nonmetals are elements that are dull, poor thermal and electrical conductors, brittle, and unmalleable.

• Metalloids are elements that have properties of both metals and nonmetals.

Multiple Choice

The elements argon, krypton, and xenon are all non-metals. What property would these elements have in common?

• Good conductor of thermal energy

• Poor conductor of electricity

• Shiny, lustrous surface

• Soft and malleable

Multiple Choice

What physical properties are used to classify elements as metals, non-metals, or metalloids?

• Color, smell, physical state

• Reactivity, streak, hardness

• Ability to burn, mass, density

• Luster, conductivity, malleability

Multiple Choice

The table shows the properties of four elements. Which element in the table is classified as a metal?

• Manganese

• Sulfur

• Silicon

• Neon