Molecules are Groups of Atoms Flashcards by Verity Russell

Q

What can atoms join together to form?

A

Molecules

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Q

What are molecules made of?

A

One or more elements

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Q

What are molecules held together by?

A

Covalent bonds

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CGP GCSE Chem (233 decks)

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The Three States of Matter - Solid, Liquid and Gas

Substances Can Change from One State to Another

Diffusion is the Movement of Particles Through a Liquid or Gas

Potassium Manganate(VII) and Water

Ammonia and Hydrogen Chloride

Bromine Gas and Air

Number of Electrons Equals Number of Protons

Atomic Number and Mass Number Describe an Atom

Molecules are Groups of Atoms

Elements Consist of One Type of Atom Only

Compounds are Chemically Bonded

Mixtures are Easily Separated - Not Like Compounds

Filtration is Used to Separate an Insoluble Solid from a Liquid

Crystallisation is Used to Separate a Soluble Solid from a Solution

You Can Use Filtration and Crystallisation to Separate Rock Salt

You Need to Know How to Do Paper Chromatography

How Chromatography Separates Mixtures...

Chromatography Can Help You to Identify Dyes

Simple Distillation is Used to Separate Out Solutions

Fractional Distillation is Used to Separate a Mixture of Liquids

The Periodic Table is a Table of All Known Elements

Elements in a Group Have the Same Number of Outer Electrons

Electron Shell Rules:

Follow the Rules to Work Out Electronic Configurations

Ionic Bonding - Transfer of Electrons

A Shell with Just One Electron is Well Keen to Get Rid...

A Nearly Full Shell is Well Keen to Get That Extra Electron...

Groups 1, 2, 6 and 7 are Most Likely to Form Ions

Ionic Compounds All Form in a Similar Way

Giant Ionic Structures Have High Melting and Boiling Points

A Covalent Bond is a Shared Pair of Electrons

Hydrogen Chloride, HCI

Carbon Dioxide, CO2

Simple Molecular Substances

Giant Covalent Structures

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Equations Show the Reactants and Products of a Reaction

Symbol Equations Need to Be Balanced

Method: Balance just ONE type of atom at a time

Isotopes are the Same Except for an Extra Neutron or Two

Relative Atomic Mass Takes All Stable Isotopes into Account

Relative Formula Mass, Mr

Finding the Empirical Formula (from Masses of Percentages)

The Empirical Formula isn’t Always the Same as the Molecular Formula

The Three Important Steps - Not to be Missed...

Percentage Yield Compares Actual and Theoretical Yield

‘The Mole’ is Simply the Name Given to a Certain Number

Nice Easy Formula for Finding the Number of Moles in a Given Mass:

Salts Can be Anhydrous or Hydrated

You Can Calculate How Much Water of Crystallisation a Salt Contains

Avogadro’s Law - One Mole of Any Gas Occupies 24 dm3

You Can Calculate Volumes in Reactions If You Know the Masses

Concentration is the ‘Amount of Stuff’ per Unit Volume

Concentration = No. of Moles / Volume

Converting Moles per dm3 to Grams per dm3

Electric Current is a Flow of Electrons or Ions

Ionic Compounds Only Conduct Electricity when Molten or in Solution

Covalent Compounds Don't Conduct Electricity

Metals are Held Together by Metallic Bonding

Metals are Good Conductors of Electricity and Heat

Most Metals are Malleable

Electrolysis is Used to Make New Substances

Electrolytes are Liquids that Conduct Electricity

In Molten Ionic Compounds There’s Only One Source of Ions

Electrolysis of Aqueous Solutions is a Bit More Complicated

Sodium Chloride:

Copper(III) Sulfate:

No. Of Electrons Transferred Increases with Time and Current

Coulombs and Faradays are Amounts of Electricity

One Mole of Product Needs ‘n’ Moles of Electrons

Use These Steps in Calculations

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The Elements can be Classified as Metals or Non-Metals

Group 0 Elements are All Inert, Colourless Gases

Group 1 Elements All React in a Similar Way with Water

Group 1 Elements Become More Reactive Down the Group

Atoms Lose Electrons More Easily Down the Group

Halogen - Seven Letters - Group 7

Hydrogen Chloride Gas Dissociates in Water...

...but Not in Methylbenzene

More Reactive Halogens will Displace Less Reactive Ones

Halogen Displacement Reactions Involve Transfer of Electrons

Acid + Metal -> Salt + Hydrogen

The Name of the Salt Depends on the Metal and Acid Used

Metals Also React with Water

The Reactivity Series - How Well a Metal Reacts

A More Reactive Metal Displaces a Less Reactive Metal

Iron and Steel Corrode to Make Rust

There are Two Main Ways to Prevent Rusting

The Atmosphere is Mostly Nitrogen and Oxygen

You can Investigate the Proportion of Oxygen in the Atmosphere Using Copper

You can Investigate the Proportion of Oxygen in the Atmosphere Using Iron or Phosphorus

You Can Make O2 in the Lab

When you Burn Something it Reacts with Oxygen in Air

You Can Collect Gases in a Test Tube

Dilute Acid reacts with Calcium Carbonate to Produce Carbon Dioxide

The Thermal Decomposition of Metal Carbonates Also Produces CO2

CO2 is used in Fizzy Drinks and Fire Extinguishers

Carbon Dioxide is a Greenhouse Gas

Increasing Carbon Dioxide is Linked to Climate Change

Flame Tests Identify Metals Ions

Some Metals Form a Coloured Precipitate with NaOH

‘Ammonium Compound + NaOH’ Gives off (Stinky) Ammonia

Hydrochloric Acid Can Help Detect Carbonates

Test for Sulfates with HCI and Barium Chloride

Test for Halides (Cl-, Brx, l-) with Nitric Acid and Silver Nitrate

There are Tests for 5 Common Gases

Wet Copper(II) Sulfate is Blue - Dry Copper(II) Sulfate is White

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Alkanes are Hydrocarbons

MethAne Formula: CH4

EthAne Formula: C2H6

PropAne Formula: C3H8

ButAne Formula: C4H10

PentAne Formula: C5H12

Alkanes are a Homologous Series

Complete Combustion Happens When There’s Plenty of Oxygen

Incomplete Combustion of Alkanes is NOT Safe

Halogens React with Alkanes to make Haloalkanes

Alkenes Have a C=C Double Bond

EthEne Formula: C2H4

PropEne Formula: C3H6

ButEne Formula: C4H8

Halogens React with Alkanes, Forming Haloalkanes

Ethanol Can Be Produced from Ethene and Steam

Ethanol Can Also be Produced by Fermentation

Both Methods have Advantages and Disadvantages...

Ethanol can be Dehydrated to Form Ethene

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The pH Scale Goes from 0 to 14

An Indicator is Just a Dye That Changes Colour

Acids can be Neutralised by Bases (or Alkalis)

Acids react with Metal Oxides to make Salt + Water...

... and with Metal Carbonates to give Salt + Water + Carbon Dioxide

Salts can be Soluble or Insoluble

Making Soluble Salts Using Acids and Insoluble Bases

Making Soluble Salts Using an Alkali

Making Insoluble Salts - Precipitation Reactions

Titrations are Used to Find about Concentrations

The Calculation - Work Out the Number of Moles

Reactions Can Go at All Sorts of Different Rates

The Rate of a Reaction Depends on Four Things:

Typical Graphs for Rate of Reaction

Three Ways to Measure the Speed of a Reaction

Change in Mass (Usually Gas Given Off)

The Volume of Gas Given Off

Reaction of Hydrochloric Acid and Marble Chips

This graph shows the effect of using finer particles of solid

Reaction of Magnesium Metal with Dilute HCl

This graph shows the effect of using more concentrated acid solutions

Sodium Thiosulfate and HCl Produce a Cloudy Precipitate

The Decomposition of Hydrogen Peroxide

More Collisions Increases the Rate of Reaction

Higher Temperatures

Higher Concentration (or PRESSURE)

Larger Surface Area

Faster Collisions Increase the Rate of Reaction

Energy Must Always be Supplied to Break Bonds

In an Exothermic Reaction, Energy is Given Out

In an Endothermic Reaction, Energy is Taken In

The Change in Energy is Called the Enthalpy Change

Energy Level Diagrams Show if it’s Exo- or Endo- thermic

The Activation Energy is Lowered by Catalysts

Bond Energy - The Amount of Energy in a Bond

Example: The Formation of HCl

You can find out Enthalpy Changes using Calorimetry

Calorimetry - Dissolving, Displacement and Neutralisation Reactions

Calorimetry - Combustion

Calculate the Heat Energy Transferred

Calculate the Molar Enthalpy Change

Reversible Reaction

Reversible Reactions Will Reach Dynamic Equilibrium

Changing Temperature and Pressure Can Get You More Product

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Most Metals are Found in Ores

Metals Often have to be Separated from their Oxides

Methods of Extraction and Linked to the Order of Reactivity

Electrolysis Removes Aluminium from Its Ore

Cryolite is Used to Lower the Temperature (and Costs)

Electrolysis - Turning IONS into the Atoms You Want

Electrolysis is Expensive - It’s All That Electricity...

The Raw Materials are Iron Ore, Coke and Limestone

Reducing the Iron Ore to Iron:

Removing the Impurities:

Iron and Aluminium have some Properties in Common

The Uses of Iron Depend on Its Properties

And so do the Uses of Aluminium

Crude Oil is Separated into Different Hydrocarbon Fractions

Burning Fuels Can Produce Pollutants

Carbon Monoxide is Produced by Incomplete Combustion

Sulfur Dioxide and Nitrogen Oxides Come from Burning Fuel

Acid Rain is Caused by Sulfur Dioxide and Nitrogen Oxides

Cracking - Splitting Up Long-Chain Hydrocarbons

Conditions for Cracking: Heat, Plus a Catalyst

Addition Polymers are Made Under High Pressure

Polymers can be Shown Using Repeating Units

Polymers can be Made by Condensation Polymerisation

Polymers Have Lots of Uses

Most Polymers are Hard to Get Rid Of

Nitrogen and Hydrogen are Needed to Make Ammonia

The Reaction is Reversible, So There’s a Compromise to be Made:

Ammonia is Used to Make Nitric Acid and Ammonium Nitrate Fertiliser

The Contact Process is Used to Make Sulfuric Acid

A Catalyst is Important When Making SO3

Modern Industry Uses Loads of Sulfuric Acid

Electrolysis of Salt gives Hydrogen, Chlorine and NaOH

The Half-Equations - Make Sure the Electrons Balance

Sodium Hydroxide

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