Chapter 3, chemical properties of slides

an element is?

The purest form of a substance that cannot be broken down into simpler substances by chemical methods.

Water is a compound made up of elements: hydrogen and oxygen. These can be separated by a process called electrolysis, whereby an electric current is used to break down water back into oxygen and hydrogen gases.
a.	Explain why water is considered to be a compound.

Water does not retain the properties of its constituents. Water is a liquid, while oxygen and hydrogen are gases

Define miscible liquids

Liquids that completely dissolve with each other and forms a homogeneous mixture. 

What are elements classified under? (the groups)

Metals or non-metals (or metalloids that possess the properties of both non-metals and metals)

Elements in groups (in the periodic table)

elements in same group have the same chemical properties

Elements in periods (periodic table)

elements in the same period have the same number of electron shells.

ATOMIC NUMBER IT IS THE?

Number of protons in an atom

ATOMIC MASS, IT IS THE?

Mass of protons and neutrons in a element

for example, H-2 or H-3 (mass of 2 and 3)

Isotopes

they are the same elements with different numbers of neutrons bur same number of protons

protons vs electrons

protons, + charge. Electrons, - charge. when number of protons and electrons is the same, it results in a neutral charge.

Metals vs non metals vs metalloids

appearance

physical state at room temperature

Melting and boiling points

heat and electrical conductivity

ductility and malleability

(the format)

METALS

• SHINY (lustrous)

• MOSTLY SOLIDS (except mercury)

• HIGH (except for sodium, potassium and mercury)

• Good

• Ductile (can be drawn into wires)

• Malleable (can be hammered into different shapes without breaking

• Sonorous (makes a ringing sound when struck)

METALLOIDS

• SHINY (lustruous)

• SOLIDS

• HIGH

• MODERATE

• Brittle (easily broken when hammered)

NON-METALS

• DULL (non-lustrous)

• gases, volatile liquids or solids

• Low (except for carbon and silicon)

• Poor (except for carbon in the form of graphite and diamond)

• Brittle if solid

Molecules

Pure substance made up of two or more atoms that are chemically combined (OF THE SAME ATOMS)

monatomic → made up of one atom (its not a molecule but)

diatomic → two atoms

Polyatomic molecules → three or more atoms that are chemically combined together.

compounds are

A pure substance made up of two or more different elements that are chemically combined in a fixed ratio by mass. (OF DIFFERENT ELEMENTS)

Compounds have (properties)

Different properties from the elements that form it

but molecules retain their unique properties

From a chemical formula we can find?

what types of elements the molecule is made up of

how many atoms of each element the molecule is made up of

the fixed ratio by mass of the elements

Thermal decomposition (def)

Thermal decomposition → uses heat to break down compounds into elements or simpler substances

electrolysis

Electrolysis → uses electricity to break down compounds into two or more simpler substances

Mixtures are/?

Mixtures are made up of two or more elements/compounds that are not chemically combined

Mixtures vs compounds

separation techniques

properties

energy changes

compositions

(formats)

MIXTURES

The components of a mixture can be separated by physical processes such as magnetic separation, filtration or distillation

The chemical properties of a mixture are the same of those of its components.

No chemical reaction takes place when a mixture is formed — usually there is little or no energy change

the components of a mixture can be mixed in any proportion

COMPOUND'

A compound can only be broken down into its elements or into simpler compounds by chemical processes (e.g. thermal decomposition or electrolysis

The physical and chemical properties of a compound are different from those of its constituent elements

A chemical reaction takes place when a compound is formed — usually there is a energy change (e.g. the reactants get hot or cold)

The elements in a compound are always combined in a fixed proportion

Solute, solution and solvent

Solute → the substance that dissolves in a solvent

solvent → the substance that dissolves the solute

solution → the mixture of the solute and the solvent

suspensions are?

it is a mixture in which insoluble substances are suspended in a liquid or gas

Solutions vs suspensions

SOLUTION

• homogeneous mixture (solute is uniformly mixed in solvent; every part of the solution looks the same)

• There is no residue when the solution is filtered

• Particles do not settle when the solution is left to stand

• Looks clear

• When light passes through the solution, light is not scattered and the light path cannot be seen

SUSPENSION

• heterogeneous (solute is not uniformly mixed in solvent, every part of the mixture looks different)

• There is residue when the suspension is filtered

• Particles settle when the suspension is left to stand

• Looks cloudy or opaque

• when light passes through the suspension, light is scattered and the light path can be seen

solubility

(ability of a solute to dissolve in a solvent)

FACTORS THAT AFFECT SOLUBILITY

Nature of solvent, nature of solute and temperature.

Factors that affect the rate of dissolving, definition of the rate of dissolving

Temperature

Size of solute particles (as they have a larger surface area that comes into contact with the solvent)

Rate of stirring

The rate of dissolving is the amount of solute that dissolves in a fixed amount of solvent, given a fixed amount of time

How to increase rate of dissolving

Increase temperature of solvent

Decrease size of solute particles

Increase rate of stirring

Units of temperature, SI unit is?

°F, °C or K

SI UNIT → K