Elements, Compounds, and MixturesMatter: Properties and Changes

Warm upObserve the pictures and use the following terms to name them: element, compound, or mixture. Explain your answer.

Warm up answers

mixtures element compound

Lesson Objectives● Classify matter as elements, compounds, or mixtures based on how the

atoms are packed together in arrangements.

● Identify the different kinds of properties used to describe matter.

Essential Question● How does the arrangement of atoms affect the classification of matter?

Properties of Matter● Chemistry is the properties of matter and how matter changes.

● The properties and changes of any type of matter depend on its makeup.

● Some types of matter are substances and some are not.

○ Substance is a single kind of matter that is pure, meaning it always has a

specific composition and properties.

○ Table salt, sugar, and baking soda are examples of pure substances because

has the same composition and properties no matter where it comes from

Properties of Matter● Every form of matter has two kinds of properties: physical and chemical

○ A physical property for oxygen is that it is a gas at room temperature

○ A chemical property for oxygen is that it reacts with iron to form rust.

Physical Properties of Matter● Physical properties is a characteristic of a pure substance that can be

observed without changing it into another substance.● Types of physical properties

○ texture ○ color○ flexibility○ physical state (solid, liquid, or gas)○ freezing point○ boiling point○ odor○ ability to conduct electricity○ magnetism○ dissolve in water

Chemical Properties of Matter● Chemical property is a characteristic of a pure substance that describe

its ability to change into different substances. ● Types of chemical properties

○ flammability

○ burning

○ rust

○ tarnish

○ combustibility

Elements● Element is a pure substance that cannot be broken down into any other

substances by chemical or physical means.● is the simplest substance● can be identified by it specific physical and chemical properties

ElementsWhat is the smallest possible piece of matter?

● Atom is the basic particle from which all elements are made.

● Different elements have different properties because their atoms are

different.

● Atom model

Parts of an atom

Parts of an Atom● Nucleus is the center of the atom. The nucleus of most atom is made up

of two kinds of particles: proton and neutrons● Protons carry a positive (+) charge.● Charge is an electrical property that can be either positive or negative.● Neutrons have no charge.● The mass of protons and neutrons are measured in atomic mass units

(amu). Each proton or neutron has a mass of about 1 amu.● Electrons are subatomic particles that exist in an area outside the

nucleus called the electron cloud. They have a negative (-) charge. The mass of electrons is insignificant compared to the mass of protons and neutrons.

ElementsWhat happens when atoms combine ?

● When atoms combine they form a chemical bond, which is the force of attraction between to atoms.

● Atoms form molecules that are groups of two or more atoms held together by chemical bonds.

Compounds● A compound is a pure substance made of two or more elements in the

compound and the ratio of atoms.

● Is represented by a chemical formula, which shows the elements in the

compound and the ratio of atoms.

○ Example of chemical formula: CO2 (carbon dioxide), H20 (water)

● When elements are chemically combined, they form compounds having

properties that are different from those of the uncombined elements.

○ Examples: Ag2S (silver sulfide), C12H22O11 (table sugar)

Compounds

Ag (silver)

S (sulfur)

Ag2S (silver sulfide)

Mixtures● Mixture is made of two or more substances - elements, compounds, or

both - that are together in the same place but are not chemically combined.

● Each substance in a mixture keeps its individual properties.● The parts of a mixture are not combined in a set ratio.

Soil

Types of MixturesI. Heterogeneous Mixtures● Is a mixture in which pure

substances are unevenly distributed throughout the mixture.

● The individual substances are easy to distinguish.

II. Homogeneous Mixtures

● Is a mixture in which substance are evenly distributed throughout the mixture.

● Example of homogeneous mixture is a solution. Solution can be ○ liquid (ice tea)○ gas (oxygen)○ solid (Brass - copper and zinc)

Homogeneous mixtures - Solution● A solution is a type of homogeneous mixture in which one substance is

completely dissolved in another substance. Solutions are usually liquids.

○ Example: sugar dissolve in water

● Solution has two part:

○ solvent is the substance that does the dissolving (water)

○ solute is the substance that dissolves (sugar)

Types of Mixture

Separating Mixtures● A compound can be difficult to separate into its elements, but a mixture is

usually easy to separate into its components because each components keeps its own properties.

● Methods use to separate mixtures:○ magnetic attraction○ sifting ○ filtration○ distillation○ evaporation

Methods to Separate Mixtures● Sifting separates the solid parts of a mixture by particles size.

○ A screen or similar devices is often used to sift materials

Methods to Separate Mixtures

● Filtration separates a solid from a liquid in a heterogeneous mixture.

Methods to Separate Mixtures

● Evaporation can be used to separate a solid from a liquid in a solution.

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