Elements, Compounds and Elements, Compounds and MixturesMixtures

Warm Up 9/25Warm Up 9/25

1. Draw a Bohr Model for Boron1. Draw a Bohr Model for Boron

2. How many valence electrons does it 2. How many valence electrons does it

have?have?

3. Do you think it is very reactive 3. Do you think it is very reactive based on based on

it’s number of valence electrons? it’s number of valence electrons?

MatterMatter

Anything that takes up space and Anything that takes up space and has mass.has mass.

There are 3 groups of matter:There are 3 groups of matter:

1. Elements1. Elements

2. Compounds2. Compounds

3. Mixtures3. Mixtures

ElementsElements

An element is the basic building An element is the basic building block of matter. You cannot break block of matter. You cannot break matter down into a more pure matter down into a more pure substance than its elements.substance than its elements.

**If you can find it on the periodic **If you can find it on the periodic table then it is an element.table then it is an element.

You can see the same sample You can see the same sample throughout (element)throughout (element)

CompoundsCompounds Two or more elements that have Two or more elements that have

chemically combined to form a chemically combined to form a different substance.different substance.

You CANNOT separate the particlesYou CANNOT separate the particles

Ex. Table salt (Na + Cl = sodium Ex. Table salt (Na + Cl = sodium chloride)chloride)

CompoundsCompoundsThe stars and circles chemically combined to form suns. This process cannot be undone.

Molecules Molecules

Molecules are when two gases Molecules are when two gases combine chemically (can either be combine chemically (can either be two of the same or two different two of the same or two different gases).gases).

Ex. HEx. H22O is one molecule of water O is one molecule of water

Pure Substance Pure Substance It’s properties are constant throughout the whole It’s properties are constant throughout the whole

sample (every single part of it is the same). sample (every single part of it is the same).

Elements and compounds are pure substances, Elements and compounds are pure substances, but mixtures are not because the properties of but mixtures are not because the properties of mixtures change throughout!mixtures change throughout!

Ex. Orange juice=mixtureEx. Orange juice=mixture Water=pure substanceWater=pure substance

Orange juice can be separated and water cannot be Orange juice can be separated and water cannot be separated in the same way. separated in the same way.

MixturesMixtures Two or more elements that are Two or more elements that are

physically combined, not chemicallyphysically combined, not chemically Can easily separate the parts Can easily separate the parts

(Ex. a cheeseburger) (Ex. a cheeseburger) Ex. Dirt and sand (if you wanted, you Ex. Dirt and sand (if you wanted, you

could easily take out the hearts)could easily take out the hearts)

Types of MixturesTypes of Mixtures There are two types of mixtures:There are two types of mixtures:

1. Homogeneous (homo means “same”)1. Homogeneous (homo means “same”)

2. Heterogeneous (hetero means 2. Heterogeneous (hetero means “different”)“different”)

Homogeneous Mixtures Homogeneous Mixtures

Have the same appearance and Have the same appearance and composition throughout.composition throughout.

Each region of a sample is identical to all Each region of a sample is identical to all other regions of the sample (one phase). other regions of the sample (one phase).

Ex. Salt water, sugar water and airEx. Salt water, sugar water and air

Heterogeneous Mixtures Heterogeneous Mixtures

Consist of visibly different Consist of visibly different substances or phases. substances or phases.

Ex. Chocolate chip cookies, oil and Ex. Chocolate chip cookies, oil and vinegar, milk, pizza and a bowl of vinegar, milk, pizza and a bowl of raisin bran cerealraisin bran cereal

SolutionsSolutions

A A solutionsolution is a mixture of two or is a mixture of two or more substances. more substances.

At least two substances must be At least two substances must be mixed in order to have a solution. mixed in order to have a solution.

Solutes vs. SolventsSolutes vs. Solvents

The substance in the smallest The substance in the smallest amount or the one that amount or the one that dissolvesdissolves or or disperses (gets mixed) is called the disperses (gets mixed) is called the SOLUTESOLUTE. .

The substance in the larger amount The substance in the larger amount is called the is called the SOLVENTSOLVENT. .

Solutes vs. SolventsSolutes vs. Solvents

In most common instances water is In most common instances water is the solvent. the solvent.

Water is considered to be the Water is considered to be the ““universal solvenuniversal solvent” because just t” because just about everything will dissolve in it. about everything will dissolve in it.

Oil is considered to be Oil is considered to be insolubleinsoluble because it will not dissolve.because it will not dissolve.

Concentrated vs. DilutedConcentrated vs. Diluted Since solutions are mixtures, their Since solutions are mixtures, their

compositions may vary over a very compositions may vary over a very wide range. wide range.

A A concentratedconcentrated solution has a solution has a relatively large (but non-specific) relatively large (but non-specific) amount of solute dissolved in a amount of solute dissolved in a solvent. solvent.

A A diluteddiluted solution has a smaller solution has a smaller quantity of solute dissolved.quantity of solute dissolved.

AlloysAlloys A homogeneous mixture of two or A homogeneous mixture of two or

more metals. more metals.

Metal mixtures can have greater Metal mixtures can have greater strength, hardness or malleability strength, hardness or malleability than by themselves.than by themselves.

Alloy ExamplesAlloy Examples Brass (copper and zinc) Brass (copper and zinc) Stainless Steel (chromium, nickel, Stainless Steel (chromium, nickel,

and iron) and iron) Sterling Silver (copper and silver)Sterling Silver (copper and silver)

Colloid Colloid ColloidColloid- a heterogeneous solution - a heterogeneous solution

with medium sized particles. with medium sized particles.

Colloid particles may be seen in a Colloid particles may be seen in a beam of light. beam of light.

Examples: Milk, dust, smoke mist, fogExamples: Milk, dust, smoke mist, fog