Inorganic - 2.1 Periodicity Flashcards
What is the atomic radius trend in the periodic table?
Atomic radius decreases across the period. This is because positive charge increases across the period due to the increasing proton number and this means the electrons are attracted close to the nucleus, making atomic radius smaller.
What is the ionisation energy trend in the periodic table?
Ionisation energy generally increases across a period due to increasing positive charge in the nucleus attracting the outer shell electrons more strongly.
What is the ionisation energy trend in the periodic table?
Ionisation energy generally increases across a period due to increasing positive charge in the nucleus attracting the outer shell electrons more strongly.
Define periodicity
Trends in element properties with increasing atomic number. The trends are caused by the changes in element atomic structure.
Define proton number
The number of protons found in the nucleus of every atom of that element. Elements are arranged in the periodic table in order of increasing proton number.
What is the trend in first ionisation energy across period three?
The general increase is caused by the increase in nuclear charge with no increase in shielding.
Atomic radius is decreasing and the outer electrons are closer to the nucleus.
Define first ionisation energy
The energy required to remove one mole of gaseous atoms to form one mole of gaseous 1+ ions
Why do group one elements have the lowest first ionisation energy?
They have the greatest atomic radius and the lowest nuclear charge
Why do group 0 elements have the highest first ionisation energy?
They have the smallest atomic radius and the highest nuclear charge
Why do group 3 elements have a lower than expected first ionisation energy?
Lower than expected due to 3p1 electron being further from the nucleus and how it has additional shielding from 3s2 inner electron so requires less energy to ionise it
Why do group 6 elements have a lower than expected first ionisation energy?
Pairing of electrons in p sub shell. Two electrons in P orbital have additional repulsion so lower energy required to remove one of the electrons decreasing the first ionisation energy.
What is the trend in the atomic radius across period three?
The atomic radius decreases across period 3.
This decrease due to the increasing nuclear charge which draws outer electrons closer to the nucleus
What is the trend of melting point of across period 3?
The melting points of metallic elements increase this is because there is an increase in the number of outer shell electrons so there is a great attraction between positive ions and delocalised electrons. The size of the ion also decreases.
Why is the melting point of silicon high?
It has a giant covenant structure and lots of energy needed to break the many strong covalent bonds
Why are the melting points of phosphorus, sulphur, chlorine and argon low?
They are simple covalent molecules and little energy is required to overcome weak VDW forces between molecules
