Elements Flashcards
What is an element?
A substance consisting of only a single type of atom
Where are elements with similar properties?
Are found in vertical groups, 1-18. (Shell = 2, 8, 8, 18)
What is the atomic radius?
The measure of the size of an atom, the distance from the nucleus to the boundary of the cloud of electrons.
Atomic radius can be obtained by taking half the measured distance between the nuclei of 2 neighbouring atoms of the same element.
What are some periodic table trends?
Atomic radius decreases from left to right due to an increase in protons and attractive force to electrons.
Atomic radius increases from top to bottom in anny group due to elements at the bottom having more electron energy shells.
What is valency?
An atoms ability to form. certain no. of chemical bonds depending on the no. of valence electrons.
What is Ionic radius?
To form ion atoms gain/lose electrons.
It changes the attractive forces thus the radius of an ion is different to the original. Ions form in different ways so there is no observable trend.
What is FIE?
First ionisation Energy: The amount of energy needed to completely remove an electron from a neutral atom. Low FIE becomes an ion (cation, positive ion) very easily.
What is SIE?
Successive Ionisation Energy: Additional electron is removed, it becomes positively charged (cation); the attraction to the remaining electrons increases, thus SIE increases.
What is electronegativity?
Ability to attract electrons to itself while bonding. It increases from left-right across a period due to more protons added increasing its positive attraction. Noble gases have 0 due to full valence and fluorine has the most. its measured using the Pauling Scale.
How are elements classified?
Can be classified as metals, non-metals or metalloids. Metals make up 75% of all elements, they are good conductors of heat, electricity, lustre, malleable and ductile.
What are alkali metals?
Occur in compounds in nature due to reactivity. Relative low melting points, can be cut with a knife.
Reactive with water to form alkaline solutions. Group 1 react to form a positive ion by losing their one valence electron which becomes easier with more electron shells and lower ionisation energy.
What are halogens?
Halogens are non-metals and toxic to life, and occur naturally as diatomic molecules. Have different characteristics which bonded with atoms from other groups (alkali halides). Melting and boiling points of the halogens increase further down the group. Halogens have high FIE and don’t lose electrons easily instead need to gain an electron.
What are the properties of oxides?
Formulas for oxides vary according to the valency of the different period 3 elements.
Changes in melting point can be attributed to the different forms of bonding between oxides. Strong metallic character elements lose electrons when boding resulting in the formation of ions. Ionic substances have high melting points as + charged metal ions are strongly attracted to the negatively charged oxide ions requiring a lot of energy to disrupt the structure.
FIE Trends
Decreases down a group due to increasing shells and takes electrons further away from the attraction of the nucleus.
Shielding Effect: Inner electrons shield outer electrons from attraction.
FIE increases from left-right across a period.
More protons are added increasing its positive attraction and energy to strip away electrons and ionize. (Electron orbitals)
What are the trends in Oxides?
Silicone dioxide is unique in period 3, it forms a giant covalent network solid. Silicon and oxygen atoms are bonded together is vast no.s, very strongly held together by covalent bonds, therefore it has a melting point. Oxides of phosphorus, sulphur and chlorine are bonded as individual molecules of only a few atoms. Molecules can be separated and melted easily due to weak intermolecular forces.
Sodium. and magnesium oxides are alkaline oxides. Aluminium oxide is an amphoteric (able to react as an acid and base) oxide, therefore it reacts with both acidic and alkaline solutions. Phosphorus, sulphur and chlorine oxides are all acidic oxides. The left-right trend shows oxides of the elements become less alkaline and more acidic.
