Chemistry Flashcards
Where do you find the Electrons
Atomic Number
What is the top number of an element
Atomic Mass
What is the bottom number of an element
Atomic Number
What is an Element
Same type of atom joined together
What is a Compound
Different type of atom joined together
Crystallization
Separating soluble substances from a solution
Distillisation
Separates liquids from solutions
What did James Chadwick discover
The Neutron
Why was the discovering of the Neutron beneficial to scientists
This allowed them to understand that it was possible for atoms of the same element to have different masses
What does the Mass Number tell you
The amount of Protons + Neutrons
What does the Atomic Number tell you
The amount of Protons
Why does Distillation work?
Because the dissolved solute has a much higher boiling point than the solvent
What are atoms made of
Protons, Neutrons and Electrons (the 3 subatomic particles)
What is found in the nucleus of an element
Protons and Neutrons
What does crystallization separate
Soluble solid from a solution
How does crystallization work
Evaporating a liquid causing the solution to become more concentrated which then makes crystals
Occasionally , what must you do when doing crystallization
Cool down the solution preventing the crystals from breaking down
How does distillation work?
Heating up the solution and the part of the solution with the lowest boiling point evaporates first
What is fractional distillation
Separating a mixture of different liquids
How does fractional distillation work
Heating a mixture of different liquids in flask attached to a fractioning column which is hottest at the bottom and is coolest at the top. Then the liquid with the lowest boiling point evaporates. After the first liquid is collected, the column temperature can be increased.
What is chromatography
Separating a mixture of soluble substances
How does chromatography work?
A pencil line is made near to the bottom of the paper where the pencil line is spotted, the paper is then placed into a solvent, the solvent seeps up the paper also bringing the dyes. The more soluble the liquid, the farther it will travel, pure substances produce only one dot
What was the atom thought as in the 19th century
In the 19th century, atoms were thought of as tiny spheres that couldn’t be separated
What did the discovery of the electron prove
The discovery of the electron proved that atoms could be divided into smaller pieces
The discovery of the electron led to
The discovery of the electron led to the making of the plum pudding model
The plum pudding model stated that
The plum pudding model stated that the atom was a ball of positive charge with negatively charged particles embedded in
What was the alpha particle scattering experiment
The alpha particle scattering experiment was an experiment where alpha particles were fired at a thin sheet of gold. The scientists thought that the alpha particles were going to fire straight through the thin gold sheet. However, this was not the case as the alpha particles reacted in a number of different ways.
What did the alpha particle scattering experiment prove?
This experiment proved that the Plum Pudding model wasn’t correct and showed that the positive charge was concentrated in one part of the atom. The concentrated positive charge was strong enough to to repel alpha particles and change their path. Although some particles went straight through the gold foil as predicted. This showed scientists that most of the atom was empty space.
What replaced the plum pudding model
The nuclear model, the nuclear model is mostly empty space, with a positively charged nucleus and negative electrons orbiting around it
Neil’s Bohr model
The Neil’s Bohr model is an improved version of the Nuclear model and suggested that electrons orbit in shells and that each electron is a fixed distance from the nucleus
Atoms have the same number of
Protons and electrons-this means that atoms have no overall charge
Radius of an atom
0.1nm
Radius of an atom’s nucleus
1x10-5 nm
How to calculate number of neutrons
Atomic mass - Atomic number
What does Ar mean
Ar is often used to represent relative atomic mass
Why was the periodic table made?
The periodic table of elements was made to sort elements in order of of groups with similar properties
What side of the staircase are metals generally found
The left side of the staircase
Why are metals metals?
The react to form positive ions
Why are non-metals non-metals
They don’t form positive ions
Metals can easily ____ their outer electrons to leave a full outer shell
Lose
Non-metals don’t ____ electrons easily
Lose, means that they cant gain a full outer shell from losing electrons so they have to gain a electron
When non-metals gain electrons they form
negative ions
Non-metals can also fill their outer shells by
Sharing electrons with other atoms
Metals towards the left of the staircase don’t have many _____ to lose
Electrons
Metals towards the bottom of the periodic table have more
Shells
The more easily an atom loses electrons the more _____ it is
reactive
What are the elements in group 0 called
The Noble gases, all Noble gases are colorless at room temperature and also unreactive meaning they exist as single atoms
What are the names of the noble gases
Helium Neon Argon Krypton Xenon Radon
Why are the Noble Gases unreactive
They are unreactive because they have a full outer energy level meaning they are very stable
Which way does the boiling points of the Noble Gases increase
They increase going down as they have increasing relative atomic mass because larger atoms have larger intermolecular forces between them
What are the group 1 elements called
Alkali metals
What are the names of the Alkali metals
Lithium, Sodium, Potassium, Rubidium, Caesium, Francium. All of these are have low densities and are soft to cut through with a knife though they are very reactive as they have only 1 electron in their outer shell
How can Alkali metals form a full outer shell
By losing 1 electron and forming a positive ion
In what direction does the order of reactivity go in group 1
They get more reactive going down because the number of shells in each atom increases
What type of compounds do alkali metals form when they react with non metals
They form Ionic Compounds because they easily lose their one outer electron to have a full outer shell. When an alkali metal loses an electron, it forms a +1 ion
When Alkali metals are put in water, they react vigorously
This reaction normally creates hydrogen gas and metal hydroxide, metal hydroxide are salts that dissolve in water that then produces alkaline solutions.
What type of oxide is formed when Alkali metals react with oxygen
Metal oxide
What are group 7 elements known as
The group 7 elements are also known as the halogens
What are the names of the Halogens
fluorine, chlorine, bromine, iodine, astatine, the Halogens are non-metals and they exist as pairs of atoms that have been covalently bonded and are non-metals
In what direction does the Halogens increase in boiling point
They increase in reactivity going down
The halogens at the top of group 7 are gasses at room temperature
The halogens at the bottom of group 7 are solids at room temperature
In what direction does the Halogens increase in reactivity
They increase in reactivity going up this is because they react by gaining 1 electron to fill their outer shell
What kind of compounds do the Halogens form when reacting with other non-metals
They can form molecular compounds they do this by sharing electrons so that both atoms can fill their outer shells.
When atoms share a pair of electrons a ____________ is formed
Covalent bond
Halogens react with _____ to form ionic compounds
Metals`
