C2 Elements, Compounds And Mixtures Flashcards
How are molecules formed?
Molecules are doomed when atoms bond together. Molecules can be made of the same element and different elements.
How big is a nanoparticle?
They are typically made of around 100 atoms and range from 1nm to 100nm in size.
What is the mass number and where is it on the periodic table?
The mass number is the total number of protons and neutrons and it is found under the element’s symbol (it is usually the larger number).
What is the atomic number and where is it on the periodic table?
The atomic number is the number of protons and it is found above the element’s symbol.
How can you find the number of neutrons?
You can find the number of neutrons by subtracting the atomic number from the mass number .
Why do neutral atoms have no charge overall?
Neutral atoms have no charge overall because they have the same number of protons and electrons. The number of electrons in a neutral atom is also equal to it’s atomic number.
How are ions formed?
Ions are formed when atoms (or groups of atoms) gain or lose electrons.
When are negative ions formed?
Negative ions are formed when atoms gain electrons and they have more electrons than protons.
When are positive ions formed?
Positive ions are formed when atoms lose electrons and they have more protons than electrons.
What are isotopes?
Isotopes are different forms of the same element, which have the same number of protons but a different number of neutrons.
How many protons, neutrons and electrons does carbon-12 have?
Protons=6
Neutrons=6
Electrons-6
How many protons, neutrons and electrons does carbon-13 have?
Protons=6
Neutrons=7
Electrons=6
Describe in terms of forces and energy need to break bonds is determined by the size of the molecule.
Smaller molecules have weaker intermolecular forces between them meaning that less energy is needed to break their bonds in order to form a gas. Larger molecules have stronger intermolecular forces since the size of the force increases as the size of the molecule increases; this means that more energy is needed to break their bonds.
What is nanotechnology?
The use and control of structures that vary on a nanoscale- 1-100 nanometers (1 millionth of a millimeter). These occur naturally in sea spray, for example, but most nanoparticles are created by scientists for nanotechnology purposes. It can also be created by accident for example as the smallest particulates from combustion of fuels.
How is nanotechnology used?
Nanoparticles can modify the properties of polymers. For example, some are used in clothes for antibacterial purposes (which prevents bad smells), and some are used in certain sports equipment (tennis rackets, golf clubs etc.) to make them lighter but stronger.
What do nanoparticles show in comparison to larger particles?
Different properties this is because they have a much larger surface area of the nanoparticles compared to their volume.
What are the dangers of Nanoparticles?
The way they affect the body isn’t fully understood, new products need to be tested thoroughly to minimize the risks.
The long-term impacts are not fully known. Many people want products containing nano technology to be clearly labeled.
Some are worried that products containing nanoparticles have been made available before the effects on human health have been properly investigated. We don’t know the long term imapacts.
Relative Atomic Mass
Bigger number on Periodic Table (Top).
Relative Formula Mass
Relative Atomic Masses added together in a compound.
Mass Conservation
Idea of atoms are never destroyed nor made, rather changed. Same mass.
Atom Economy
% of Reactants changed to Useful Products.
Waste Product
Product which isn’t needed
Chromatography
The extraction of a substance or chemical from a compound.
Pure Substances
Can’t be seperated by Chromatography. Specific melting and boiling point.
Inpure Substances
Can be seperated by Chromatography. Has a low melting point and a high boiling point.
Allotropes
Different structural forms of the same element in the same physical state.
Diamonds
Lustrous, Colourless and very hard Due to strong Covalent Bonds. Doesn’t conduct electricity due to lack of free ions or electrons.
Lustrous
Sparkly.
Strong Covalent Bonds
High Boiling Point, Hard to break, good cutting tools.
Weak Covalent Bonds
Low Boiling Point, Easy to break, not very good cutting tools.
Graphite
Black, Opaque, Shiny, 3 Covalent bonds that are layered, layers are very weakly held together. Good for Pencils and Lubrication. High melting point. Only 3 of 4 electrons are used in bonding, so lot of delocalised electrons are present, conducting electricity.
Giant Molecular Structure
Diamond and Graphite are examples of this.
Fullerenes
Molecules of Carbon, shaped like closed tubes, or hollow balls. Can cage other molecules.
Fullerenes could lead to…
Slow release drugs.
Fullerenes can…
Join together to form nanotubes
Nanotubes
Tiny Hollow Carbon Tubes. These have a huge surface area, so could be used to make Industrial Catalysts if these molecules were attached.
What is relative atomic mass?
The total number of protons and neutrons in an atom.
What is an element’s atomic number?
The number of protons in an atom (equal to the number of electrons).
What is a group?
A vertical column of elements on the periodic table. There are 8- Group 0-Group 7. All the elements within a group have similar properties, and the number of the group corresponds to the number of electrons in the outer shell (e.g. Group 1 elements have 1 electron on their outer shell).
What is a period?
A horizontal row of elements on the periodic table. All the elements in a period have the same number of electron shells (e.g. elements in the fourth period have 4 electron shells).
What did Mendeleev do?
He took the work done by scientists before him, such as Doberiner and Newlands, and organised the known elements into order by atomic weight and into groups with similar properties. He left gaps, where he thought other undiscovered elements would be, and correctly predicted the properties of those elements. What he had created was a table of the elements, very similar to what we use today.
What is an atom made up of?
A small central nucleus, consisting of protons and neutrons.The nucleus is positively charged, the whole of the mass is concentrated there too and it’s small in comparison to the rest of the atom. Electrons are arranged in shells surrounding the nucleus. The number of protons and electrons are equal, so it has a neutral charge. The volume of their orbit determines how big the atom is.
What is a proton?
A small atomic particle, with a positive charge of +1 and a relative mass of 1. They are heavy.
What is a neutron?
A small atomic particle, with no charge and a relative mass of 1. They are heavy
What is an electron?
A small atomic particle, with a negative charge of -1 and a negligible relative mass of 0.0005. They are tiny.
What is electron configuration?
A series of numbers (e.g. 2,8,1- sodium) showing how the electrons are arranged in their shells. The first shell holds 2 electrons, and the following shells can hold 8. For the first 20 elements, the configuration increases by one as you go along the period.
What is Group 1 on the Periodic Table?
The alkali metals- a group of 6 metals (lithium, sodium, potassium, rubidium, caesium). The density increases the further down the group you go, and the melting/boiling points decrease. They all have one electron on the outer shell, and the reactivity increases the further down the group you go- the further the outer shell from the nucleus, the weaker the force of attraction between them, and the easier it is for the electron to be lost.
What is Group 7?
The halogens- a group of 5 non-metals (fluorine, chlorine, bromine, iodine, astatine). All the elements travel around in diatomic pairs (they exist in pairs of atoms), and the density and melting/boiling points increase as you go down the group. As you go down the group, the outermost electron shell gets further away from the nucleus. Each element has 7 electrons on the outer shell, so it is trying to attract another to it. The further away, the weaker the force of attraction, so the less reactive it is.
What are ions?
Atoms that have either gained or lost electrons, meaning the number of protons and electrons is no longer equal, so the atom has a positive or negative charge.
What are positively charged ions?
Atoms that have lost electrons.
What are negatively charged ions?
Atoms that have gained electrons.
What is ionic bonding?
A metal and non-metal react, and electrons transfer from one atom to another, giving each a full outer shell and an electric charge. Ionic compounds are crystals, because the ions are arranged in a regular lattice. Examples include any salt or halide.
Relate electron shells to their reactivity
An “just” incomplete shell are keen to gain an electron to fill a shell whereas a shell with just one electron is keen to get rid of it. This is why Alkali metals lose an electron so they become positive ions and why Halogens gain an electron to become negative ions.
Relate the nucleus to electron shells and their reactivity
The first electron shell will have stronger forces of electrostatic attraction in comparison in comparison to shells that are further away which means they are easier to be lost.
What happens when sodium and chlorine bond?
They bond ionically to form sodium chloride. The sodium has one electron on its outer shell, which is transferred to the chlorine atom. This gives both a full outer shell, and the sodium becomes positively charged, while the chlorine has a negative charge.
What charge do ionic compounds have?
They are electrically neutral substances- they have no charge. This is because they have equal amounts of positive and negative charge.
What did Dmitri Mendeleev do?
Lined up all elements according to their RAM leaving spaces for elements that had not been discovered.
Covalent bond is formed between…
Two non-metals.
Ionic bond is formed between…
Metal and Non-metal
Ionic bond is also known as
Electrovalent bond
Colvalent bond melting/boiling point
Low
Ionic bond melting/boiling point
High
Colvalent bond examples
Methane, hydrochloric acid.
Ionic bond examples
Sodium chloride, sulphuric acid.
Colvalent bond room temp state
Liquid or gas
Ionic bond room temp state
Solid
Colvalent intermolecular strength
Much stronger than ionic bonds
H2O is liquid at room temperature
Yes even though it has a lighter mass than O2, N2 etc.
When cooled to 0 C water
Expands, thus ice is less dense than water and floats.
Water can dissolve
Ionic compounds
Why is seawater salty?
Water in rivers dissolves salts and washes them into the sea.
Why is ice less dense than water?
Water molecules are angled so when they line up in ice they create a very open structure.
Evapourites
When water evaporates, ionic compounds crystallise.
Giant ionic lattice
The cubic shape that ionic bonding forms.
Diamond vs Graphite hardness
Hard, soft
Diamond vs Graphite Melting point
Graphic higher but similar
Diamond vs Graphite Boiling point
The same
Diamond vs Graphite Solubility
Both are insoluble
Diamond vs Graphite Conductivity
Low, high
Diamond - Giant covalent structure
Covalent bonds join each carbon atom to four other carbon atoms in three dimensions making tetrahedron shapes.
Graphite - Giant covalent structure
Covalent bonds join each carbon atom to three other carbon atoms in two dimensions making tessellating hexagons. Each atom has a spare electron which enables graphite to be conductive.
Quartz
It has a giant covalent structure similar to diamond and it is insoluble.
Alloy
A mixture of metals
Metallic bonding
The metal atoms lose their outer - and form + ions. The delocalised - drift around the lattice of + ions and hold the ions together.
Describe filtration
Used to separate an insoluble solid from a liquid
Filtration can be used when the product is an insoluble solid, so needs to be separated from the liquid reaction mixture. E.G in the pharmaceutical industry it is used to separate out aspirin
Can be used for purification as well. E.G solid impurities in the reaction mixture can be separated out using filtration
Describe evaporation and crystallisation
Used to separate a soluble solid from a solution
Heating the solution evaporates it, leaving behind solid crystals of the product
Also useful for purifying the product. Crystals have a regular structure that the impurities can’t fit into
This process is often continually repeated to improve purity. Products are dissolves and then crystallised again in a process of recrystallation
Describe drying
Used to dry to product by removing excess liquid
Products can be dried in a drying oven
Products can also be dried using desiccators. These are containers that contain chemicals like silica gel to remove water from their surroundings, keeping the product dry
