Presentation on Elements-mixtures-compounds Notes -1

8/16/2019 Presentation on Elements-mixtures-compounds Notes -1

1/31

ElementsCompounds

Mixtures


2/31

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 atomsbonded together, called molecules.

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

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


3/31

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 byphysical or chemical means.

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

Compounds can be broken into simpler substances by chemical means.


4/31

Classifying Matter

Matter

Pure Substances Mixtures

Elements Compounds

Homogeneous Heterogeneous

On Periodic Table

Have a Symbol

Have a Formula

Not UniformThroughout


5/31

Mixtures and Pure Substances1. 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.


6/31

Elements

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

Air-Water- Fire-Earth

2. Chemists have identified 90 naturallyoccurring elements , and syntheticallyproduced about +28 others.

1. An element is made of one kind of atom2. Found on the Periodic Table3. All elements are made of atoms.4. Atoms of the same element are alike.5. Atoms of different elements are different.


7/31

Three Types of Elements

1. Metals Solids, malleable, ductile, goodconductors, mercury the only liquid atroom temperature. Largest group of

elements.

2. Nonmetals Solids and gases, brittle, poorconductors. Bromine the only liquidat room temperature.

3. Metalloids Share properties of both. Smallestgroup of elements.


8/31

Properties of Metals1. Metals are good conductors

of heat and electricity.

2. Metals are shiny, metallicluster.

3.

Metals are ductile (can bestretched into thin wires).

4. Metals are malleable (canbe pounded into sheets).

5. A chemical property ofmetal is its reaction withwater which results incorrosion.

malleable

malleable

ductile


9/31

Properties of Non-Metals1. Non-metals are poor conductors of

heat and electricity.

2. Non-metals are not ductile ormalleable.

3. Solid non-metals are brittle and

break easily.4. They are dull.

5. Many non-metals are gases.

Sulfur


10/31

Properties of Metalloids1. Metalloids (metal-like) have properties

of both metals and non-metals.

2. They are solids that can be shiny ordull.

3. They conduct heat and electricitybetter than non-metals but not as wellas metals.

4. They are ductile and malleable.

SiliconThe most important metalloidfor its use in computer chips


11/31


12/31

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

Water on the surface and in the air as clouds and fog is madeup 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 ofjust six elements.


13/31

What Is A Compound?

1. A compound is a pure substance that is createdby two or more elements chemically reactingand bonding together .

A. Ex: NaCl, H 2O, CO 2, NH 3, NaHCO 3, and C 6H12O6

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


14/31


15/31

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/soapsIII. Have a slippery feeling to themIV. Taste bitterV. Strong bases are caustic (cause chemical burns)

Common BasesNaOH Drano (Drain Cleaners)Al(OH)3 Mg(OH)2 in antacid tabletsCa(OH) 2 used to help concrete set-up


16/31


17/31

Why Do Compounds Form?

Compounds form to allow elementsto become more stable.

A. Na is flammable when it comes incontact with H 2O, and Cl 2 is a toxicgas

B. NaCl is a very stable compound that isneither flammable nor toxic in normalquantities.

Compounds that are extremely unstablewill break down to form the more stableelements- EXPLOSIVES!!!!

ChlorineSodium


18/31

Compounds

1. Sodium is an element.

2. Chlorine is an element.

3. When sodium andchlorine bond they makethe compound sodiumchloride, commonlyknown as table salt.

Compounds have different propertiesthan the elements that make them up.

Table salt has different properties than sodium, anexplosive metal, and chlorine, a poisonous gas.


19/31

What Do Compounds Have To Do With My Life?Compounds are the substances that

make up ALL living and non-living things.


20/31

What Is A Mixture?

1. Mixtures- two or more things combine physicallyin 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 mixturesB. Heterogeneous mixtures


21/31


22/31


23/31


24/31

Colloids and the Tyndal Effect

Tyndal EffectThe microscopic particles of a

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

–it’s called the Tyndal Effect


25/31

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

formed when one substance dissolves inanother.

2. The size of the solute in a solution ion, atomor molecular, so solutions never settle –theyalways still mixed.

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


26/31


27/31

Alloys

Brass is an alloy of copperand zinc.

Stainless steel is a mixtureof iron and chromium.

Air is a solution of oxygen and othergases dissolved in nitrogen.


28/31

Heterogeneous Mixture - Suspension1. Suspension – the solute is unevenly

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

2. ExamplesA. Paint

B.

Chex Mix: You may find a different number ofpretzels or Chex cereal in each handful;therefore, the mixture is unevenly distributed

C. Italian Salad dressingD. Chocolate Milk


29/31

Compounds vs MixturesCompounds Mixtures

Elements chemicallybonded together

Not chemicallycombinedCombine in setproportions- HAVE A

FORMULA Can combine in anyproportion

Separatedchemically

Separatedphysically


30/31


31/31

Classification of Matter

Pure Substances

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

b) Non-Metals i. Acid i. Solutionc) Metalloids ii. Base ii. Colloid

iii. Salt b) Heterogeneous

b) Organic i. Suspension

Presentation on Elements-mixtures-compounds Notes -1

Documents

Transcript of Presentation on Elements-mixtures-compounds Notes -1