Solids, liquids, and gases Flashcards
What are the four state symbols
Aqueous (aq), Liquid (l), Gas (g), solid (s)
Describe structure of a solid
Particles arranged in a fixed lattice
Particles can vibrate
Properties - Fixed shape Fixed volume Do not flow Higher density than liquids/ gases
Describe structure of a liquid
Particles close together
Particles can move about
Properties - Shape can change Fixed volume Can flow Higher density than gas, lower than solids
Describe structure of a gas
Particles far apart
Particles move quickly
Properties - Shape can change Volume can change Can flow Lower density than solid/ liquid
Definition of melting
Solid changes into liquid (at the melting point)
Definition of boiling
Liquid changes into a gas (at the boiling point)
Definition of freezing
Liquid changes into solid (at the freezing point)
Definition of condensation
Gas changes into liquid (at the boiling point)
Definition of sublimation
Solid changes into gas (without going through liquid state)
Definition of diffusion
The process by which particles in liquids and gases mix together or spread out by colliding with each other.
Particles move down a concentration gradient rom a high concentration to a low concentration.
What factors affect rate of diffusion
Tempurature - faster diffusion with higher temp
Molecular mass - higher molecular mass = slower diffusion
What is an experiment to demonstrate diffusion
There is a tube which at one end had cotton wool soaked in HCl and at the other soaked in Ammonia solution. a white ring of ammonia chloride forms where the two gases meet showing one has diffused quicker than the other
What is Brownian motion
The random movement of large particles in a gas or suspended in a liquid.
What causes Brownian motion
Caused by collision of molecules in the surrounding gas or liquid with the large particles
What evidence is there for Brownian motion
Pollen grains move randomly in water when observed under microscope
Dust particles move randomly in the air
What is an atom made up of
Protons, electrons and neutrons
What is a proton
Mass - 1
Charge - +1
Location - nucleus
What is a neutron
Mass - 1
Charge - 0
Location - nucleus
What is an electron
Mass - 1/2000
charge - -1
location - Shells orbiting the nucleus
What is the nucleon number
Total number of protons and neutrons
What is the proton number
Number of protons
What are valency electrons
The electrons in the most outer shell
How is the stability of atoms related to their electronic structure
Atoms with a full outer shell are stable
this is achieved by losing or gaining electrons
What is an atom
The smallest particle of a chemical element, which cannot be broken down any further (by chemical means)
What is an element
A group of atoms which all have the same number of protons
What are isotopes
Atoms with the same number of protons but different numbers of neutrons
what is a compound
A substance in which two or more elements are chemically combined
What is a mixture
A combination of two or more substances that are not chemically combined
What is an ion
An atom where the number of electrons is different from the number of protons, so it has an overall charge
Cation - A positively charged ion
Anion - A negatively charged ion
What is an allotrope
Different forms of the same element e.g. diamond and graphite
Radioisotopes
Unstable isotopes which give out radiation when they decay, They can be used for Tracers, Radiotherapy, Sterilisation
What is ionic bonding
Occurs between metal and non-metal
Attraction between positive metal ions and negative non-metal ions
How are ions formed
Metals lose electrons to form positive ions
Non-metals gain electrons to form negative ions
What is covalent bonding
Occurs between non-metals
Covalent bonds are a shared pair of electrons
What are two types of covalent structure
Simple molecular
Giant covalent lattice
What is a molecule
a group of atoms being held together by covalent bonds
What are intermolecular forces
weak forces between covalently bonded molecules
Name three covalent macromolecules
Diamond, Graphite, Silicon (IV) Oxide
Properties of diamond
Hardest known substance, Does not conduct electricity, very high melting point, cut diamonds sparkle
Properties of Graphite
Soft and slippery, conducts electricity, dark in colour
Properties of silicon (IV) dioxide
Hard (can scratch things), doesn’t conduct electricity, ,light passes through it, high melting point
What is metallic bonding
Occurs in metallic elements, The attraction between +ve metal ions and -ve electrons
Describe properties of metals
High mp and bp malleable and ductile good electrical conductors good heat conductors insoluble in water
What is an alloy
A mixture of a metal with other elements
Why are alloys more useful than pure metals
harder and stronger than pure metals, some are more resistant to corrosion
Define exothermic reaction
Reaction that gives out energy (temp increase)
Define endothermic reaction
Reaction that take in energy from surroundings (temp decrease)
What is bond energy
The energy required the break a particular bond
Equation for calculating energy change of reaction
Total energy of bonds broken - total energy of bonds formed
What four ways can energy be released
Burning fuels, nuclear fuels, fuel cells, electrochemical cells
What are “Photochemical reactions”
reactions which obtain the energy they need from light
What is a reversible reaction
A reaction that can take place in both directions
What is meant by equilibrium
The forward and backward reactions that take place at the same rate. No overall change in conc.
How is equilibrium affected by concentration, tempurature, pressure
equilibrium moves to the products side if reaction conc. increases, the product concentration decreases.
If temp increases it becomes a endothermic reaction. If pressure increases equilibrium position moves to the side.
How is yield related by equilibrium position
The yield will be higher if the equilibrium if closer to the products side
Define “rate of reaction”
amount of reactant used up per unit time
what factors affect rate of reaction
increase the concentration, increase the tempurature, increase surface area, use a cataylst
What is “collision theory”
Where for two particles to react successfully they must collide with sufficient energy to break the necessary bonds
What is “empirical formula”
Shows the simplest ratio in which atoms combine to form a compound
What is “molecular formula”
shows the actual numbers of atoms that combine to form a molecule
What is “structural formula”
shows how the atoms are arranged in the molecule
What is “relative atomic mass”
The average mass of naturally occurring atoms of an element relative to the mass of carbon-12
What is “Relative formula mass”
the sum of the relative atomic masses
What is a “mole”
the amount of a substance that contains the same number of particles as the number of carbon atoms in 12g of carbon-12
What is “Avogadro constant”
The number of particles in one mole of an element or compound
What is “molar solution”
A solution that contains 1-mole of solute per dm3 of solution, written as 1mol/dm3
What is “molar volume of gas”
1 mole of gas occupies 24dm3 at room tempurature and pressure
What is the equation for number of moles
mass/molecular mass
What is the equation for concentration
molar concentration = amount of solute(g)/volume of solution
mass conc. = amount of solute(mol)/ volume of solution
What is the equation for moles of a gas
volume of a gas (in dm3)/24dm3
What is the equation for percentage yield
actual mass obtained/ theoretical mass
What is the equation for percentage composition
total Ar of element in compound/ mr of compound x 100
What is the equation for percentage purity
mass of substance in mixture/total mass of mixture x 100
What does aqueous mean
Dissolved in water
