Peridoic Table Flashcards
First ionisation energy
The minimum energy required to remove the most loosely bound electron from a NEUTRAL GASEOUS atom in its ground state
Decreases down a group
Increases across a period
Electron configuration
Shows the arrangement of electrons in the atom of an element
Aufbau principle
When building up the electron configuration of an atom in its ground state, the electrons occupy the lowest energy level available
Hund’s Rule of Maximum Multiplicity (bus seat rule)
When 2+ orbitals of equal energy are available, the electrons occupy them singly before filling in pairs
Pauli Exclusion Principle
No more than 2 electrons can occupy an orbital and they must have an opposite spin
An element
A substance that can’t be split into simpler substances by chemical means
Newland’s Octaves
Arrangements of electrons when the 1st and 8th elements have similar properties
Triad
A group of 3 elements of similar properties, where the Relative Atomic mass of the middle element is the average of the other two elements
Mendeleev’s Periodic Law
When elements are arranged in order of increasing Relative Atomic mass (atomic weight) the properties of the elements recur periodically
Recur periodically
Repeat at regular intervals
Atomic number of an atom
The amount of protons (H+) in the nucleus of an atom
Modern periodic table
An arrangement of atoms in order of increasing atomic number
Modern Periodic Law
When elements are arranged in order of increasing atomic number, the properties of the elements recur periodically
Mass number
The sum of protons+neutrons in the nucleus
Isotopes
Atoms of the same element with different mass numbers due to a different number of neutrons in the nucleus
Relative Atomic mass
The average of the mass numbers of all the isotopes as they occur naturally, taking their abundance’s into account and expressed on a scale where the atoms of carbon-12 has a mass of 12 units
Principle of Mass Spectrometry
Charged particles moving in a magnetic field are deflected to different extents according to their mass numbers
Electronegativity
The relative attraction an atom in a molecule has for the shared pair of electrons in a covalent bond
Atomic radius
Half the distance between the nuclei of 2 atoms of the same element that are joined by a single covalent bond
Value of atomic radius….increase/decrease
Increases down the group (screening effect)
Decreases across a period (no increase in screening effect)
Second ionisation
The energy required to remove an electron from an ion with one positive(+) charge in the gaseous state
Value of electronegativity….increase/decrease
Increases across the periods (decreasing atomic radius/ increasing effect of nuclear charge)
Decreases down the groups (increasing atomic radius)
Value of first ionisation energy…increase/decrease
Increases across a period (decreasing atomic radius)
Decreases down a group (increasing atomic radius/screening effect)
4 original elements (Greek philosophers)
Water, fire, earth, air
Contribution of Robert Boyle
Defined an element as: a substance that can’t be split into simpler substances by chemical means
Why is water not an element.
Water is a compound and not an element as it can be split into simpler substances, Hydrogen and Oxygen
How did Davy discover potassium (K)?
Passing electricity through a compound of K
Also discovered: Na, Mg
Dobereiner’s contribution
Discovering triads
E.g. li, Na, K
Atomic weight=
Relative Atomic mass
Important chemists into devising the periodic table
Dobereiner (triads)
Newland (octaves)
Mendeleev (Mendeleevs Periodic Law)
Moseley (Atomic number)
Problem with Newland’s Octaves?
Noble gases weren’t in it because they hadn’t been discovered
Didn’t leave gaps
Summarise Mendeleev’s work/Periodic Table
- Left gaps
- Elements with similar properties in same vertical column (properties repeated periodically)
- Predicted properties of undiscovered elements (predicted properties of Germanium & Gallium before discovery)
- Reversed the order of some elements
Why is Tellirium before Iodine?
Mendeleev arranged his table in order of increasing atomic weight, but Te has a higher weight than I and yet is before it, as he realised the properties were more important than their weights, by reversing them the elements were in groups of similar properties
Moseley’s contribution to the Periodic Table?
- Discovered the atomic number of an atom
- Arranged the table in order of increasing atomic number (elements now fall naturally into groups, no reversing)
- Confirmed Mendeleev was right placing Te before I
Differences between Mendeleev’s Periodic Table and the Modern Periodic Table?
1. Mendeleev: increasing atomic weight Modern: increasing atomic number 2. Mendeleev: gaps Modern: no gaps 3. Mendeleev: some elements not discovered (noble gases) Modern: more elements
Important uses of the Periodic Table?
Finding atomic no. and mass no.
Finding relative Atomic mass
Electron configuration
Number of neutrons?
Mass no.-Atomic no.
Who built the mass spectrometer?
William Aston- to measure the masses of atoms
Aston also discovered isotopes
Isotopes of carbon?
Carbon-12, carbon-13, carbon-14
3 Isotopes of hydrogen?
Hydrogen-1, hydrogen-2, hydrogen-3
5 processes in mass spectrometry
Vaportpisation Ionisation Acceleration Separation in a magnetic field Detection
VIASD (Volumes In Acids Stay Donating)
What is a mass spectrometer used for?
To identify isotopes, their abundance’s and the relative atomic mass of an element
To identify unknown compounds
Use of mass spectrometer for identifying unknown compounds?
Chromatography- to detect banned drugs taken by athletes
Drug tests- drugs leave traces in the addict’s hair
Bohr’s electronic configuration of Potassium?/ showing the no. Of electrons in each main energy level
2,8, 8, 1
Electronic configuration of Cr and Cu (odd ones out)
Cr: 1s2, 2s2, 2p6, 3s2, 3p6, 4s1, 3d5
Cu: 1s2,2s2, 2p6, 3s2, 3p6, 4s1, 3d10
(This provides extra stability- 4s sublevel being half filled)
Why is the 4s sublevel filled before the 3d sublevel?
4s sublevel has less energy
When are sublevels extra stable?
When they completely filled or half filled
Ion
A charged atom
(Has lost or gained electrons)
Atom loses electrons—> positively charged
Atom gains electrons—> negatively charged
Reactivity of alkali metals…increases/decreases?
Very reactive (low first ionisation energy+a single electron in the outer energy level to be lost)
Increases down the group (increasing atomic radius)
