Elements, Compounds, Mixtures Flashcards
What is the structure of an atom
Protons and Neutrons inside a dense core at the centre of the atom called the nucleus (quite small compared to rest of atom)
Electrons spread out around the edge of the atom and orbit the nucleus in layers called shells.
What is the Relative Mass and Charge of a Proton
Mass = 1 Charge = +1
What is the Relative Mass and Charge of a Neutron
Mass = 1 Charge = 0
What is the Relative Mass and Charge of an Electron
Mass = almost 0 Charge = -1
How does an atom become an ion
Atoms have no electrical charge so they are neutral. The charge of the electrons and protons are the same so therefore the number of electrons and protons are always equal. If electrons are added or removed then the atom becomes charged as the positive and the negative don’t cancel out anymore and that’s how it becomes an ion.
What is the Electron Configuration
1st Shell - up to 2 electrons
After a shell is full the electrons go into the next shell
2nd Shell and all the rest - up to 8 electrons
When writing this … (e.g. If an atom has an atomic number of 9, it has an electron configuration of 2,7)
How do you draw an electron configuration diagram
Represent the nucleus as a small circle (labelled) and draw rings around it to represent the shells and an ‘X’ to represent an electron in one of those shells. (have a key to show what each symbol means) For 1st Shell draw an X on the top of the shell and the bottom of the shell (if there are 2). For all the other shells draw an X in the 4 main directions and if there are more electrons than 4 put an X next to one of the X’s already present
What does a Symbol of an Element Consist of
Atomic Mass
Atom Symbol
Atomic Number
(in this order with Atomic Mass at the top of the box and Atomic Number at the bottom)
What is the Atomic Mass (A)
Number of Protons + Number of Neutrons (if you can’t remember this just remember it’s usually the bigger number out of Atomic Mass and Atomic Number)
What is the Atomic Number (Z)
Number of Electrons (or Protons - they have the same number of them in an atom)
What is special about Hydrogen
Has no neutrons but still has 1 proton; found in the nucleus of the atom and 1 electron found in the in the 1st shell
What is an Isotope
Atoms of the same element (same number of protons) but a different number of neutrons, therefore giving it a different mass number (e.g. Chlorine has 2 isotopes, Cl = 35 and Cl = 37)
What is a group in the periodic table
A column, there are 8 in total, starting from 1 on the left and going to 8/0 in the very right, not counting any of the transition metals in the middle as groups
What is a period in the periodic table
A row, there are 7 in total, starting from 1 on the very top with just Hydrogen and Helium in it going down to row 7 at the bottom of the periodic table.
What is an Element
A substance which can not be broken down into anything simpler; made of only one type of atom. Can exist as single atoms e.g. K, or bonded with other atoms to form molecules e.g. O₂
What is a Compound
Contains 2 or more elements which have been chemically bonded. Elements in a compound are in a fixed ratio which is shown by the formula e.g. water(H₂0) there are 2 Hydrogen atoms for every oxygen atom. Are difficult to separate and must undergo chemical change for the preceding to happen
What is a Mixture
2 or more elements or compounds that are not chemically bonded. Easier to separate than compounds
Acid + Metal
Salt + Hydrogen
Acid+ Metal Carbonate
Salt + Water + Carbon Dioxide
Water + Metal
Metal Hydroxide + Hydrogen
What do all acids contain
Hydrogen
What are Group 2 Metals also known as
Alkaline Earth Metals
How is the Periodic Table structured
Elements with similar properties form columns called groups. All elements in a group have the same number of Valence electrons (electrons in the outermost shell) The number of valence electrons is equal to the atom’s main group number
Atoms are also grouped in rows called periods. The period that an element is in dictates its number of electron shells. (e.g. Na, which is in period 3, has 3 shells)
Separation Techniques
Filtration/Decanting, Evaporation, Simple Distillation, Fractional Distillation, Separating Funnel, Chromatography
Filtration/Decanting
Separates Insoluble Solid + Liquid (e.g. Sand and water)
Pour mixture down a filter funnel with filtration paper around the inside
Evaporation
Separation Solution, obtains solute (e.g. Salt from a salt solution
Heat up solution until it is at the boiling point of the liquid. Liquid evaporates, solid remains
Simple Distillation
Separates Solution, obtains solvent and solute (e.g. Water and Salt separated from a salt solution)
Evaporation, but there is a condenser on the end to get solvent as well
Fractional Distillation
Separates 2 Miscible Liquids (liquids that can mix together e.g. Ethanol and Water), obtains both liquids separately
Heats the mixture to a heat to the boiling point of the liquid which has a lower boiling point (e.g. heats up to 78°C which is boiling point of ethanol but not to 100°C which is the boiling point of water) so that liquid will evaporate then condense again in the condenser.
Separating Funnel
Separates 2 immiscible liquids (liquids that cannot mix together e.g. Oil and Water)
Lets out the heavier liquid from below and stops before lighter liquid goes through
Chromatography
Separates multiple soluble solids (e.g. Mixture of food dyes)
Dots are drawn on a pencil line near the bottom of a piece of paper. Then the paper is slightly submerged in a solvent like water. The water travels up the paper and separates the colour into all its different pigments.
