Paper 1/ 2: Section 1- Key Concepts of Chemistry Flashcards
A chemical _______ are shown through word or symbol equations. ______ equations need to be balanced- having the same number of _____ of each _______ on both sides of the equation.
- equations
- Symbol
- atoms
- element
What are the four state symbol and what do they tell you?
State symbols show the state of a substance in an equation:
(s)- solid
(l)- liquids
(g)- gas
(aq)- aqueous
List the eight common hazard symbols:
. Oxidising
. Toxic
. Harmful
. Corrosive
. Environmental
. Flamable
At the start of the 19th century, how did John Dalton describe an atom?
Described an atom as solid spheres. Suggesting that different spheres made up the different elements.
Describe the theory and backstory behind the ‘Plum Pudding Modlel’.
In 1897, J J Thomson concluded from his experiments that atoms weren’t solid spheres. His measurements of charge/ mass showed the presence of small, negatively charged particles- electrons. Then creating knew theory of the ‘Plum Pudding Modlel’.
How did Rutherfords gold foil experiment disprove the ‘Plum Pudding Model’?
In 1909, Rutherford conducte an experiment where they fired positively charged alpha particles at a thin sheet of gold. While most passed through the foil, more than expected were deflected (some even backwards). This ment the ‘Plum Pudding Model’ couldn’t be right.
What theory did Rutherford use to explain his new evidence?
The theory of the nuclear atom- a tiny positively charged nucleus, surrounded by a ‘cloud’ of electrons.
What theory is the closest to the version of the atom we see today? What did it suggest?
The Bohr Model:
. Suggested all electrons were contained in the shells or only existed in fixed orbits.
. Proposed the idea that each shell has a fixed energy.
List the relative mass and charge of the three subatomic particles that make up the atom:
PARTICLE MASS CHARGE
Proton: 1 +1
Neutron: 1 0
Electron: 1/ 1865 -1
Where is most of the mass of an atom concentrated?
The nucleus
Why does every atom have no overall charge?
They contain equal numbers of positive protons and negative electrons. These opposite charges cancel each other out making the atom neutral.
What is the atomic number and where can you find this on the nuclear symbol?
The number of protons an atom has, which determines an elements place in the periodic table.
. Its the higher number on the nuclear symbol
What is the mass number and where can you find this on the nuclear symbol?
The total number of protons and neutrons in a nucleus.
. Its the lower number on the nuclear symbol.
Isotopes are different forms of the same _______ that contain equal numbers of _______ but different numbers of ________ in their nuclei.
- element
- protons
- neutrons
What is the relative atomic mass and where can you find this on the nuclear symbol?
The ratio of the average mass of one atom of an element to one twelfth of the mass of an atom of carbon-12.
. Its the higher number on the nuclear symbol.
How do you calculate the relative atomic mass (Ar)?
Ar= total mass of atoms x total number of atoms/ 100
How can you work out the Ar from isotopic abundances?
. Multiply each relative isotopic mass by its different quantities (isotopic abundances), and add up the results.
. Divide by the sum of the abundances.
How do you calculate isotopes?
Isotopes= the atomic mass- atomic number
How does the existence of isotopes result in the relative atomic mass of some elements not being whole numbers?
The relative atomic mass is the average mass of different isotopes of the element, therefore it is not always a whole number.
Who made the first periodic table and how was it arranged?
In 1869, Dmitri Mendeleev created the first proper periodic table. He sorted the elements based on their properties, and in order of atomic mass.
What are the three electron shell rules?
- Electrons always occupy shells (also known as energy levels)
- The lowest energy levels are always filled first.
- 1st shell has 2 electrons only, the 2nd only 8 shells and the 3rd only 8 shells too.
How can you work out the electronic configuration?
- The atomic number tells you the amount of protons, and protons= electrons.
- Then follow the electronic configuration rules.
What are ions and when do they form?
Ions are charged particles (in groups or as single atoms)- when atoms lose or gain electrons.
What is an anion?
Negative ions that form when atoms GAIN electrons.
What is a cation?
Positive ions that form when atoms LOSE electrons.
The ______ of electrons lost or gained is the same as the ______ on the ion.
- number
- charge
What is an ion?
An atom or group of atoms with a positive or negative charge.
Metal atoms ____ electrons to form positively charged ions. Whereas, non-metal atoms ____ electrons to form _________ charged ions
- lose
- gain
- negatively
Why are group 1, 2, 6 and 7 most likely to form ions?
or elements in groups 1 and 2 the number of electrons lost is the same as the group number.
Simlarly, for groups 6 and 7, the number of electrons gained is equal to (8 - group number).