1. // S1.1 Models of the particulate nature of matter

chem from lynn

Mixtures

• Components may be elements or compounds.

  • Are not chemically bonded together and not in a fixed ratio.

  • Retain their individual properties.

• Homogeneous: all the components of a mixture are in the same phase. e.g. Air

• Heterogeneous: the components of a mixture are in different phases.

Exothermic

Reaction releases energy

Endothermic

Eeaction takes up/ requires energy

electron affinity

mininum energy released when 1 mole of e- is added to 1 mol of atoms (g)

ionization energy

minumun energy needed to remove 1 mol of e- from 1 mol of atoms (g)

ionic radious

radious of an ion, this is different from atomic radious due to change in amout of electrons, positive ions usually get smaller, negative bigger

Absorbance

to take light in and not reflect or refract it

Precision

a measure of how close a series of measurements are to one another

accuracy

how close a measurement is to the true value

analog measurements

analog measurements

manual measuring, measurement where you Estimate what the device says.
- uncertainty is half of the smallest increment

digital devices

round +/- 1 to smallest increment (e.g. analytical scale, digi thermostat)

uncertainty

an estimate of how much a measured or calculated value differs from a true value

absolute uncertainty

uncertainty associated with a measurement

Percentage uncertainty

The uncertainty given as a percentage of the measurement taken (absolute uncertainty/ measurment x 100)

structural formula

a formula that shows the arrangement of atoms in the molecule of a compound

deposition

gas to solid

Sublimination

solid to gas

Vaporization

Liquid to gas

condensation

Gas to liquid

melting

solid to liquid

freezing

liquid to solid

solid

defined shape and volume, low Ek

liquid

flexible shape that adjusts to container, fixed volume, middle Ek

gas

moves freely and adjusts to volume of container, high Ek

Kinetic Molecular Theory

• All matter is made up of particles that are constantly moving.

• The energy of the particles depends upon the absolute temperature.

• A change of state may occur when the energy of the particles is changed.

• The average amount of empty space between particles generally increases as matter moves from the solid to the liquid and gas phases.

• There are forces of attraction between particles which become stronger as the particles move closer together.

solvation

seperation method: dissolving a mixture in a soluvent
-based on solubility, less soluble substance stays undissolved longer

Filtration

seperation method: a solid can be saparated from a liquid using a filter (filter paper) which lets the liquid pass through
-based on different particle size

Suction filtration

seperation method: (very tiny ) solid can be saparated from a liquid using a filter (filter paper) which lets the liquid pass through
-based on different particle size

Melting point determination

Checking a substances purity

Pure substances: fixed sharp melting point, value can be compared with the literature value.

Impure substances: Lower melting point and tend to melt over a wider temperature range.

Sample is placed in a small melting point tube and the melting point is determined either by using commercial melting point apparatus or by attaching it to a thermometer in an oil bath that is gradually heated.

decantation

seperation method: insoluable solids can be seperated from liquid by letting it sink to the bottom and then taking out liquid
-based on different particle size and density

recystalization/drying

seperation method: by heating a solution to the boiling point of the soluvent, this then evaporates until only solid ( salt) is left
-based on different B.p.

distilation

seperation method: a mixture of two liquids can be seperated by heating the micture until the B.P of one liquid is reaches, this will evaporate out of the mixture and is caugth using a conderncer
-based on different B.P

Chromatography

seperation method: Ink or other liquid mixtures can be seperated using water a paper, by letting the water suck into a paper stained with ink, the ink paticles are seperated and carried by the water. the smallest particles go the furthest and the others stay back

Retardation factor (R_F)

Substances can be identified by their RF values. lf two substances have similar RF values in one solvent, the paper can be turned 90° and a different solvent used (two-way chromatography)

extraction (solid)

seperation method: by dissolving a mixture of a soluable and insoluable solid, these solids can be seperated as the soluable solid will dissolve into water, the insoluable solid can be filterd out
-based on different soluablitliys

extraction (liquid)

seperation method: two immensible liquids can be seperated using a seperatory funnel

centrifugation

seperation method: small particles can be seperated from liquids using centrifugation. (e.g. red blood cells from plasma)
-based on different densitys

pure substance

A substance made of only one kind of matter and having definite properties.

element

only one type of atom

compound

a substance made of two or more atoms combined in specific ratio

mixture

two or more pure substances mixed with individual properties, seperatable with physical methods

homogenous

uniform in composition

heterogenous

non uniform compositions, different through out

colloids

mixtures that look homogenous but are heterogenous

isoelectrons

atoms with the same electron configuration
(e.g. K+ und Cl-)

diatomic

A molecule consisting of two atoms in nature

halide

ion of halogen

reduction

gain of electrons, (oxidation agent)

oxidation

loss of electrons, (reducing agent)

replacement/ displacement reaction

Where are compound breaks apart and forms a new compound plus a free reactant

In such a reaction, the element and compound combine. An element separates from the compound and combine with the element to give a new compound as a product. The element is replaced in the compound. For that reason it is also called the replacement reaction

Halogens commonly go through this process; when helogen with a samller NC and one with a bigger NC come close the bigger one gets oxidixed/ replaced by the smaller one which gets reduced (oxidation agent)

metalloid

an element that has properties of both metals and nonmetals

one-half the distance between the nuclei of two atoms of the same element when the atoms are joined

nuclear charge

number of protons in the nucleus

shielding effect

Refers to the protection of valence electrons by core electrons in inner energy levels

(trend down the period)

electromagnetic spectrum

the complete range of electromagnetic waves placed in order of increasing frequency

the specific energies an electron in an atom or other system can have (kinda same as shells is bohrs model)

absorb

to take in

photon

the smallest particle of light

quantize

electrons can only exist at specific energy levels, separated by specific intervals, so the values

Quantized means that it is measured in discrete values. For example, energy levels of electrons are quantized so there are specific values that an energy level can have, such as n=1,2,etc. it can't just be any number.

Cation

Positively charged ion

Anion

Negatively charged ion

elastic collision

A collision in which colliding objects bounce off without lasting deformation or the generation of heat.

solution

A mixture that forms when one substance dissolves another.

solute

A substance that is dissolved in a solution.

solvent

the substance in which the solute dissolves

Molarity

(concentration) — The number of moles of solute per liter of solution

Standard solution

a solution of known concentration

mass percentage

the number of grams of solute in each 100 g of solution

phenolphthalein indicator

Acid - Colorless, alkali( basic) - pink