Periodicity Flashcards
Describe the connection between atomic number and the order of elements in the Periodic Table.
Elements in the periodic table are arranged in increasing order of atomic number.
What is a period in the Periodic Table?
A row of elements arranged by increasing atomic number.
What is a group in the Periodic Table?
Vertical columns containing elements with similar chemical properties.
Why do elements in the same group have similar properties?
They share a common number of outer electrons in their shells.
What is the change of outer electrons across a period?
An increase in the number of outer electrons occurs across a period causing a move from metallic to non-metallic characteristics.
What is Group 8 known as?
Noble Gases.
What is Group 7 known as?
Halogens.
What is covalent radius?
A measurement of atomic size which is half the distance between the nuclei of two bonded atoms in an element.
What happens to the covalent radius across a period?
In your answer, explain why.
Going along a period, covalent radius decreases. With the addition of a proton, the positively charged nucleus pulls outer electrons closer to the centre therefore decreasing the atom’s size.
What happens to the covalent radius down a group?
In your answer, explain why.
Down a group, covalent radius increases. There is an increased number of energy levels of electrons causing them to be further away from the nucleus, therefore being less attracted to it’s core causing the atoms to be larger.
What is ionisation energy?
The amount of energy needed to remove one electron from each atom in a mole of gaseous atoms.
What happens to ionisation energy down a group?
In your answer, explain why.
Ionisation energy decreases down a group. There are more energy levels so they are less attracted to the positive charge of the nucleus therefore, less energy is required to remove one electron.
What happens to ionisation energy across a period?
In your answer, explain why.
Ionisation energy increases across a period. There outer-most electrons are more attracted to the positive nucleus and therefore, take more energy to remove one electron.
What is electronegativity?
A measure of the ability of an atom in a molecule to attract the bonding electrons towards itself.
What happens to electronegativity down a group?
In your answer, explain why.
Electronegativity decreases down a group. As atomic size increases, the electrons are less attracted to the positive core as they are further away from the nucleus.
