Chemistry Flashcards
What is an element?
A substance containing only one type of atom.
What is an atom?
Smallest particles to ever exist.
What is a compound?
Two or more different elements, chemically joined together.
What is a mixture?
Two or more different substances that are not chemically combined and can be separated physically.
What does the atomic number show?
Number of protons + Number of electrons
What does the atomic mass show?
Number of protons + Number of neutrons
How many electrons can one shell hold?
2 in the first layer, 8 in the rest
What are diatomic elements?
Elements that exist in pairs, like Halogens.
Who made the periodic table of elements?
Dmitri Mendeleev
What is an electronic structure? Give an example.
Shows the amount of electrons each atom has in its shell or shells. Chlorine = 2.8.7 (2 electrons in the first shell, 8 in the second, 7 in the last)
What is a relative atomic mass?
Average mass of atoms of an element.
What is the relative formula mass?
Sum of the relative atomic masses of the atoms in the numbers.
Properties of non metals?
Dull, brittle, poor conductors of heat & electricity, low density, low melting point
Properties of metals?
Malleable (flexible), shiny, conductor of heat & electricity, high melting point, high density
What is an ion?
Atoms that have lost or gained electrons to make their outer shell equal.
How are ions different in a diagram?
Surrounded by square brackets e.g [Li]
What is ionic bonding?
When metal bonds to a non metal (transfer of electrons)
What is covalent bonding?
Two or more non metals bonding to a non metal (sharing of electrons)
What is metallic bonding?
When metal bonds to a metals.
What happens when you’re forming ions with metals?
Form positive ions
What happens when you’re forming ions with non metals?
Either form negative ions or they don’t form any ions.
Do noble gases have a full outer shell?
Yes
Are noble gases reactive?
No, because they are balanced.
What group are noble gases in?
0
Boiling and Melting points and density decrease as you go down group 0 (noble gases)?
False! They increase in melting, boiling point and density.
Examples of noble gases?
Helium, Neon, Argon, Krypton and Xenon
What does group number show us?
How many electrons in the outer shell
What does period number show us?
How many electron-containing shells the element has
Why are alkali metals given their name?
Because they form an alkaline solution when reacted with water
What is aqueous?
When a substance dissolves in water, it becomes an aqueous solution.
Brief description of: solvent, solution and solute.
A solute is a substance that dissolves in a solvent to form a solution
What group is alkali metals in?
Group 1
What are Halogens?
Halogens are chemical elements that form a salt when reacted with water. They are also diatomic
What group is Halogens in?
7
Examples of Halogens?
Fluorine, Chlorine, Bromine, Iodine, Astatine
Properties of Halogens?
1)Reactive
2)Melt and Boil points increase down the group
3)High electronegativity (measure of an atom’s ability to attracted shared electrons to itself)
4) Oxidation decreases down the group
How do you know if a compound ends in an -ide?
If it has 2 different types of atoms.
How do you know if a compound ends in a -ate?
If it has 3 or more different types of atoms and one is oxygen.
What is transition elements?
Group of elements known for their colourful compounds and ability to form multiple oxidation states.
What group is transition elements in?
Groups 3-12
Properties of some transition elements?
Cobalt - hard,brittle, slow to react, high melt & boil point
Nickel - hard & malleable, not react with water, magnetic at room temp
Iron - conductor of heat and electricity, high density, melt and boil points.
Chemical properties include?
Reactivity, Solubility, Toxicity, Reactivity, Flammability and Heat of Combustion
Examples of transition elements?
Cobalt, Nickel, Chromium, Manganese, Copper and Iron
What is simple molecular substances?
Substances that are made up of molecules that are held together by strong covalent bonds, but weak intermolecular forces.
What are nanoparticles?
Small particles that is between 1 to 100 nanometres in size.
What is an allotrope?
compounds made up of the same atoms but in a different structure.
Examples of allotropes? * brief description and their uses*
Diamond
1) Made from only carbon atoms
2)Each carbon atom covalently bonds to 4 carb atoms
3) No free electrons, cant conduct electricity
Uses:
1) cutting tools
2) glass cutters
3) oil rig drills
4) jewellery
Graphene:
1) Single layer of graphite
2) Delocalised electrons
Uses:
1) Electronics
