Elements Compounds Mixtures

Mixtures - Elements - Compounds

Chemists like to classify things.

One way that chemists classify matter is by its composition.

All matter can be classified as mixtures, elements and compounds.

1.  All matter is composed of atoms and groups of atoms bonded together, called molecules.

A.  Substances that are made from more than one type of atom bonded together are called compounds.

B.  Compounds and elements that are combined physically, but not chemically, are called mixtures.

Chemists can classify matter into-

Mixtures Two or more substances that are not chemically combined with each other- they are mixed together.

Mixtures can be separated by physical means.

The “things” in a mixture keep their individual properties.

Elements Simplest form of pure substance.

They cannot be broken down into anything else by physical or chemical means.

Compounds Pure substances that are composed of two or more elements chemically bonded together.

Compounds can be broken into simpler substances by chemical means.

Classifying Matter

Matter

Pure Substances Mixtures

Elements Compounds

Homogeneous Heterogeneous

On Periodic Table

Have a Symbol Have a Formula

Not Uniform Throughout

Mixtures and Pure Substances

1.  A mixture has unlike parts and a composition that varies from sample to sample.

2.  A heterogeneous mixture has physically distinct parts with different properties, non-uniform throughout.

3.  A homogeneous mixture is the same throughout the sample.

4.   Pure substances are substances with a fixed composition.

Elements and Compounds ARE pure substances.

Elements

1.  Science has come along way since the Greek Theory of all matter composed of-

Air-Water- Fire-Earth

2.  Chemists have identified 90 naturally occurring elements, and synthetically produced about +28 others.

1.  An element is made of one kind of atom 2.  Found on the Periodic Table 3.  All elements are made of atoms. 4.  Atoms of the same element are alike. 5.  Atoms of different elements are different.

Three Types of Elements

1.   Metals Solids, malleable, ductile, good conductors, mercury the only liquid at room temperature. Largest group of elements.

2.   Nonmetals Solids and gases, brittle, poor conductors. Bromine the only liquid at room temperature.

3.   Metalloids Share properties of both. Smallest group of elements.

Properties of Metals 1.  Metals are good conductors

of heat and electricity.

2.  Metals are shiny, metallic luster.

3.  Metals are ductile (can be stretched into thin wires).

4.  Metals are malleable (can be pounded into sheets).

5.  A chemical property of metal is its reaction with water which results in corrosion.

malleable

malleable

ductile

Properties of Non-Metals 1.  Non-metals are poor conductors of

heat and electricity.

2.  Non-metals are not ductile or malleable.

3.  Solid non-metals are brittle and break easily.

4.  They are dull.

5.  Many non-metals are gases.

Sulfur

Properties of Metalloids 1.  Metalloids (metal-like) have properties

of both metals and non-metals.

2.  They are solids that can be shiny or dull.

3.  They conduct heat and electricity better than non-metals but not as well as metals.

4.  They are ductile and malleable.

Silicon The most important metalloid for its use in computer chips

The elements of- Aluminum, Iron, Oxygen, and Silicon make up about 88% of the earth's solid surface.

Water on the surface and in the air as clouds and fog is made up of hydrogen and oxygen.

The air is 99% nitrogen and oxygen.

Hydrogen, oxygen, and carbon make up 97% of a person.

Thus almost everything you see in this picture us made up of just six elements.

What Is A Compound?

1.  A compound is a pure substance that is created by two or more elements chemically reacting and bonding together.

A.  Ex: NaCl, H2O, CO2, NH3, NaHCO3, and C6H12O6

B.  ALL compounds can be written as a FORMULA, which will show the elements present and in what proportion.

Types of Compounds

Inorganic Compounds a)   Acid Form a H+ ion in solution

I.  H+ are chemically very reactive II.  React with metals to form hydrogen gas III.  Strong acids are corrosive IV.  Taste sour

Common Acids HCl Hydrochloric Acid - Stomach Acid H2SO4 Sulfuric Acid - Car Battery H2CO3 Carbonic Acid - Soft Drinks HNO3 Nitric Acid H3PO4 Phosphoric Acid - Some Soft Drinks HC2H3O2 Acetic Acid - Vinegar (organic acid)

Types of Compounds

Inorganic Compounds b) Base Form a (OH)- ion in solution

I.   (OH)- are chemically very reactive II.   Dissolve fats and oils, makes them good cleaners/soaps III.   Have a slippery feeling to them IV.   Taste bitter V.   Strong bases are caustic (cause chemical burns)

Common Bases NaOH Drano (Drain Cleaners)

Al(OH)3 Mg(OH)2 in antacid tablets

Ca(OH)2 used to help concrete set-up

Types of Compounds Inorganic Compounds

c) Salt Compounds that form ions in solution, made from metals and nonmetals

Common Salts NaCl table salt

KCl salt substitute

CaCl2 De-Icer

CaSO4 Dry Wall MgSO4 Epsom Salt

IONS Atoms that have lost OR gained electrons, making them have a positive or negative charge.

ORGANIC Compounds Carbon based compounds, these types of compounds are associated with living things.

Why Do Compounds Form? Compounds form to allow elements to become more stable.

A.  Na is flammable when it comes in contact with H2O, and Cl2 is a toxic gas

B.  NaCl is a very stable compound that is neither flammable nor toxic in normal quantities.

Compounds that are extremely unstable will break down to form the more stable elements- EXPLOSIVES!!!!

Chlorine Sodium

Compounds

1.  Sodium is an element.

2.  Chlorine is an element.

3.  When sodium and chlorine bond they make the compound sodium chloride, commonly known as table salt.

Compounds have different properties than the elements that make them up. Table salt has different properties than sodium, an explosive metal, and chlorine, a poisonous gas.

What Do Compounds Have To Do With My Life? Compounds are the substances that make up ALL living and non-living things.

What Is A Mixture?

1.  Mixtures- two or more things combine physically in no specific proportions. They just mix.

2.  A mixture is not chemically combined.

3.  Mixtures can be separated by physical means- such as filtration, distillation, and chromatography

4.  Mixtures can be divided into two groups A.  Homogenous mixtures B.  Heterogeneous mixtures

Mixtures 1.  Hydrogen is an element.

2.  Oxygen is an element.

3.  When hydrogen and oxygen bond they make the compound water.

4.  When salt and water are combined, a mixture is created. Compounds in mixtures retain their individual properties. The ocean is a mixture.

What Is a Homogenous Mixture?

1.  A homogeneous mixture is a mixture that is evenly distributed- THE SAME THROUGHOUT

2.  Homogeneous mixtures called solutions or colloids. A.  Solution = Solute + Solvent

I.  Solute: substance being dissolved II.  Solvent: substance doing the dissolving

3.  The solvent is present in greater quantity

4.  The solute is present in the lesser quantity

A.  Ex: Salt water ➜ Salt = solute Water = solvent

Colloid – Homogeneous Mixture 1.  In a colloid the particles are mixed together but

not dissolved.

2.  The particles are microscopic size so they are kept permanently suspended.

3.  A colloid will not separate upon standing.

4.  The particles are constantly colliding, and this allows a colloid to scatter light – thus colloids often seem cloudy.

Blood is a colloid. The red blood cells are the microscopic particles.

Colloids and the Tyndal Effect

Tyndal Effect The microscopic particles of a

colloid reflect the light that passes through it so you see the “beam of light”

–it’s called the Tyndal Effect

Solutions - Homogeneous Mixture 1.  A solution is a type of homogeneous mixture

formed when one substance dissolves in another.

2.  The size of the solute in a solution ion, atom or molecular, so solutions never settle –they always still mixed.

3.  Solutions never settle and solutions never show the Tyndal effect.

Types of Solutions

Solute Solvent Example

Molten metals in metals are called alloys.

An ALLOY is a solid solution.

Alloys

Brass is an alloy of copper and zinc.

Stainless steel is a mixture of iron and chromium.

Air is a solution of oxygen and other gases dissolved in nitrogen.

Heterogeneous Mixture - Suspension 1.  Suspension – the solute is unevenly

distributed, has to be shaken or stirred to get a uniformity in it.

2.  Examples A.  Paint B.  Chex Mix: You may find a different number of

pretzels or Chex cereal in each handful; therefore, the mixture is unevenly distributed

C.  Italian Salad dressing D.  Chocolate Milk

Compounds vs Mixtures Compounds Mixtures

Elements chemically bonded together

Not chemically combined Combine in set

proportions- HAVE A FORMULA Can combine in any

proportion

Separated chemically

Separated physically

Elements, Compounds, and Mixtures

1.  Mixtures can be separated by physical means.

2.  Compounds can only be separated by chemical means.

3.  Elements are pure substances. When the subatomic particles of an element are separated from its atom, it no longer retains the properties of that element.

Classification of Matter

Pure Substances

1. Elements 2. Compounds 3. Mixtures a) Metals a) Inorganic a) Homogeneous

b) Non-Metals i. Acid i. Solution

c) Metalloids ii. Base ii. Colloid

iii. Salt b) Heterogeneous

b) Organic i. Suspension