Matter Flowchart

MATTER

Can it be physically separated?

Homogeneous Mixture

(solution)

Heterogeneous Mixture Compound Element

MIXTURE PURE SUBSTANCE

yes no

Can it be chemically decomposed?

noyesIs the composition uniform?

noyes

A. Matter Flowchart

Examples:

graphite

pepper

sugar (sucrose)

paint

soda

element

hetero. mixture

compound

hetero. Mixture

Solution(homogeneous mixture)

C. Johannesson

Pure Substances

Element composed of identical atoms EX: copper wire, aluminum foil

Pure Substances

Compound composed of 2 or more elements

in a fixed ratio

properties differ from those of individual elements

Chemically combined and must be chemically separated

EX: table salt (NaCl)

Mixtures

Variable combination of 2 or more pure substances.

Physically combined and separated

Heterogeneous Homogeneous

Mixtures

Solution homogeneous very small particles no Tyndall effect Tyndall Effect

particles don’t settle EX: rubbing alcohol

What are the differences between an element, compound and mixture?

Matter has properties

Two basic types of properties that we can associate with matter.

Physical properties

Chemical properties

Physical Properties

Anything that can be observed without changing the identity of the substance. (Tends to be measurable.)

• melting point• boiling point• electrical conductivity• color

• density • thermal conductivity• ductility• malleability

Chemical Properties

The way a substance may change or react to form other substances

• heat of combustion• reactivity with water• PH• Oxidation• Flammability

• Reactivity to other chemicals

Physical Changes

Do NOT CHANGE THE TYPE OF MATTER

Nothing new or different is formedCould be a change in:

Mass Volume Density Change in state Color Shape

Size

Examples of Physical Changes

Boiling Freezing Dissolving Breaking Making a mixture

2 or more types of matter (substances) mixed together Not in specific amounts Can be separated physically

Chemical Changes

The composition of the substance changes.

The substances present at the beginning of the change are not present at the end; new substances are formed. The change cannot be “undone.”

Picture from www.chem4kids.com

Chemical Changes

Evidence of a chemical reactionFormation of gas Formation of precipitate Change in color Change in energy

Endothermic Absorbs heat energy (gets cold) Exothermic Releases heat energy (gets hot)

Chemical Changes

Atoms are re-arranged, NOT created or destroyed

Law of Conservation of Matter

Matter is conserved type of atoms does not change

Nothing is created or destroyed

Atoms and Ions• An atom has a zero net charge• How does an ion become an atom? Loses

Electrons• What element am I?• Protons=8 Electrons=8 Neutron=9• Are these the same element?• Proton = 9 Electron =10 Neutron = 10• Proton = 9 Electron=9 Neutron = 11

Part 2 Notes: Compounds• Noble gases-located… Right most column of the PT• They are the only elements that tend to exist …as

isolated atoms• Molecule: the smallest electrically neutral unit of a

substance that still has properties of that substance; two or more atoms that are covalently bonded and act as a single unit

• Diatomic molecule: molecule made of two atoms

• H2 O2 F2 Br2 I2 N2 Cl2 (At2)

Molecular or covalent compounds: compounds composed of neutral molecules

• Relatively low MP and BP (below 300°C)• Exits as gases or liquids because of low BP/MP• Composed of generally 2 or more nonmetallic

elements• The smallest unit is a molecule

Ions: atoms or groups of atoms that have a positive or negative charge

• Ionic compounds: compounds composed of two or more ions that have opposite charges

• MP and BP: fairly to very high• Exists as solid crystals• Composed of a metallic ion with a nonmetallic

ion in a ratio where there is a balance of opposite charges

• Smallest unit called formula unit (do not abbreviate)

• Chemical formula: shows the kinds and numbers of atoms in the smallest representative unit of the substance

• Molecular formula: shows the kind and numbers of atoms present in one molecule of the substance

• Formula unit: smallest whole number ratio of positive and negative ions in the smallest electrically neutral portion of a compound which is ionically bonded

Pure Substances

Law of Definite Composition

A given compound always contains the same, fixed ratio of elements.

Law of Multiple Proportions

Elements can combine in different ratios to form different compounds.

Pure Substances

For example…

Two different compounds, each has a definite composition.

Law of Definite proportions-does not depend on the amount of substance

• Example: Given the formulas CO and CO2, what do you know about these compounds based on the Law of Definite proportions? The ratio of C to O within each compound will be constant-but it will be different from one compound to another

Example 1:

• Compound A: 2.41gC = 0.748 gC/gO 3.22g O

Compound B: 6.71g C = 0.375 gC/gO 17.9g O

A:B 0.748 gC/gO = _2_ 0.375 gC/gO 1 The mass ratio of C per gram of O in compound A to that of compound B is 2:1

Or…

H2O and H2O2

H:O H:O 2:1 2:2 2g:16g 2g:32g

Example 2

N:O is 7:468g of N+O – 42g of N = 26g of O

N:O is 42g/26g so 1.6gN per gram of O

No, this is not nitrous oxide since it is not in a 7:4 mass ratio