chemistry Flashcards
acid + metal becomes…
salt + hydrogen gas
acid + metal hydroxide becomes…
salt + water
acid + metal oxide becomes…
salt + water
acid + metal carbonate becomes…
salt + water + carbon dioxide
acid + metal hydrogen carbonate
salt + water + carbon dioxide
Strong acids
Will always ionise 100% of the molecules to become H+ ions
Weak acids
Ionise less than 100% of the molecules into H+ ions
rate of reaction equation
How to find average rate of reaction
Gradient between 2 points
How to find instantaneous rate of reaction
Gradient of a tangent of a point
Concentrated acids
High amount of the substance in a set volume
Dilute acids
Small amount of substance in a set volume
Collision theory
Reactant particles need to collide, when they collide, they need to:
- Be in the correct orientation
- Have enough energy (activation energy) to break apart bonds
Ways to change the rate of reaction
- Concentration
- Temperature
- Surface area
- Catalyst
How does increasing concentration change the rate of reaction
- More particles in a given volume
- Increases the frequency of successful collisions
How does increasing temperature change the rate of reaction
- Increases the kinetic energy of the particles (moving around faster so have more activation energy)
- Increases the frequency of successful collisions
How does increasing surface area change the rate of reaction
- Increases the surface area that reactants react with
- Increases the frequency of frequent successful collisions
How does adding a catalyst change the rate of reaction
- Breaks/ weakens the bonds of reactants but does not get used in reaction
- Rearranges particles to be in correct orientation
Catalyst definition
A substance that is added to speed up the rate of reaction without being a part of the chemical reaction
Properties of acids
- Produce hydrogen ions when dissolved in water
- Sour in taste
- Molecular in structure
- Dissolves substances
Properties of bases
- Produces hydroxide ions when dissolved in water
- Feels soapy
- Alkaline
0-6 on the pH scale is…
Acidic
8-14 on the pH scale is…
Basic
Electron definition
- Negative charge
- Smaller than protons and neutrons
- Sit in the shells of an atom
Protons
- Have a positive charge
Neutrons
- Have a neutral charge
Nucleus
- Centre of the atom
- Has a positive charge
- Contains protons and neutrons
What are ions?
- A version of an atom that becomes charged through gaining or losing electrons
- Its goal is to have a full outer shell
Cations
- Positively charged ions (more protons than electrons)
- Mostly metals
Anions
- Negatively charged ions (more electrons than protons)
- Mostly non-metals
Polyatomic ions
OH(-): Hydroxide
CO3(2-): Carbonate
HCO3(2-): Hydrogen carbonate
Ionic bonding
The bonding between a metal and a non-metal through the transfer of electrons
Displacement reactions
A displacement reaction occurs when the more reactive metal is placed into a solution with a less reactive metal
Reactivity series of elements (from most to least)
Potassion, Sodium, Calcium, Lithium, Magnesium, Aluminium, Zinc, Iron, Tin, Lead, Copper, Gold
Properties of ionic compounds
- Lattice structure alternating between cations and anions
- High melting and boiling points
- Crystalline solids
- Conducts electricity when in molten or aqueous state
- Hard
- Brittle
What is shown by the periods on the periodic table?
- Horizontal rows
- Indicate the number of shells occupied by electrons
What is shown by the groups on the periodic table?
- Vertical columns
- Indicate the number of valence electrons that are in the atom
Metallic bonding
Bonding between metals, through electrostatic attraction between delocalised electrons and metal cations.
Properties of metallic compounds:
- Good conductors of heat and electricity
- High melting and boiling points
- Malleable
- Ductile
- High density
- Lustrous
Covalent bonding
- Occurs between 2 non-metals
- Electrons are ‘shared’ between atoms so they have a full outer shell
- Can join two or more elements with covalent bonding
Atomic number
Indicates the number of protons (and electrons) in an atom
Mass number
Indicates the number of protons and neutrons in an atom
Types of heat treatment of metals
- Annealing
- Quenching
- Tempering
Annealing
- Heated until red hot, called slowly
- Large crystals with small gaps
- Softer, more ductile
Quenching
- Heated until red hot, cooled quickly in cold water
- Small crystals, more gaps
- Harder but more brittle
Tempering
- Quenched, then warmed to lower temperature, cooled slowly
- Reduces brittleness
- Remains hard
Law of conservation of mass
Atoms cannot be created or destroyed
Why do ionic compounds have high melting and boiling points?
- Large amounts of energy required to break electrostatic attraction between oppositely charged ions (strong ionic bonds)
Why do ionic compounds have crystalline solids?
- Due to their regular, repeating arrangement of ions known as an ionic lattice
Why do ionic compounds conduct electricity when aqueous or molten?
- To conduct electricity, particles muct be charged and free-moving
- When solid, the ions are trapped in the lattice structure (not free-moving)
- BUT in a molten or aqueous state, the positive and negative ions are free to move in a uniform way towards electricity
Why are ionic compounds hard?
- The surface of ionic compounds is not easily scratched as a strong force is needed to disrupt the ionic bonding
Why are ionic compounds brittle?
- When enough force is applied to distort the ionic lattice, ions of like charge become adjacent, repel and cause the ionic lattice to shatter
Why are metals good conductors of electricity?
- Delocalised electrons are free to move to the positive electrode
- Are attracted due to their opposite charges
Why are metals good conductors of heat?
- Heat causes the cations and electrons to vibrate more rapidly
- Delocalised electrons move through the lattice, passing heat on
Why are metals malleable and ductile?
- A force can push petal ions past each other as the sea of delocalised electrons holds the layers together
Why are metals lustrous?
- Delocalised electrons reflect photons of light
Why do metals have high melting and boiling points?
- Strong electrostatic bonds require large amounts of energy to break
Why do metals have high density?
- A lot of mass in a small volume
- Cations are very close together
Ways to extract metals
- Mining
- Roasting in air
- Smelting
- Electrolysis
Electrolysis
- Using electrodes to collect the metal cations on the negative terminal
Roasting in air
- Heating metal to a high temperature below melting point in the presence of air
