Chemistry: 2.1 Periodicity
This flashcard set explores the structure of the periodic table, including the arrangement of elements by atomic number, the definitions of periods and groups, and the concept of periodicity. It also explains the trend in first ionisation energy across a period, noting specific dips between certain groups.
In what order are elements arranged in the periodic table
Increasing atomic number
Key Terms
In what order are elements arranged in the periodic table
Increasing atomic number
Period
Row of elements
Group
Column or elements
Periodicity
The study of repeating trends and patterns in the periodic table
Trend in first ionisation energy across a period
Increases across the period with a dip between group 2 and 3 and between group 5 and 6
First ionisation energy
The energy needed to remove one electron from each atom in one mole of gaseous atoms
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| Term | Definition |
|---|---|
In what order are elements arranged in the periodic table | Increasing atomic number |
Period | Row of elements |
Group | Column or elements |
Periodicity | The study of repeating trends and patterns in the periodic table |
Trend in first ionisation energy across a period | Increases across the period with a dip between group 2 and 3 and between group 5 and 6 |
First ionisation energy | The energy needed to remove one electron from each atom in one mole of gaseous atoms |
Why does first ionisation energy increase across a period |
|
Why does atomic radius decrease across the period |
|
What are cations like in size relative to their atoms | Smaller |
Why are cations smaller than their atoms | Lose electrons and so lose a shell Same protons attracting fewer electrons |
What are anions like in size relative to their atoms | Larger |
Why are anions larger than their atoms | Gain electrons so same number of protons attracting more electrons |
| The power of an atom to attract the pair of electrons in a covalent bond |
What is the trend in electronegativity across a period | Increase |
Why does electronegativity increase across a period | Number of protons increase Attraction on outer electrons increases |
Why is there variation in melting and boiling points across a period | Changes in structure and bonding |
What is the structure in Na, Mg and Al | Giant lattice |
What bonding Na, Mg and Al |
|
Trend in boiling and melting points from Na to Al | Increase |
Why do melting and boiling points increase from Na to Al | Metallic bonds increase Charge increases More delocalised electrons Attraction between ions and delocalised electrons increases |
structure and bonding of silicon | giant covalent |
melting and boiling point of Si | v high |
why does Si have high m and b point | huge numbers of strong covalent bonds needed to be broken |
structure of phosphorus, sulphur and chlorine | simple covalent |
melting/boiling points of sulphur, phosphorus and chlorine | relatively low |
why are melting/boiling points relatively low in phosphorus, sulphur and chlorine | weak VDW forces between molecules need to be overcome |
in what order to boiling/melting points increase in sulphur, phosphorous and chlorine | chlorine>phosphorus>sulphur |
why do boiling points increase from chlorine>phosphorus>sulfur | molecules get larger so more electrons involved in bonding- VDWs greater |
structure of Ar | atoms |
melting/boiling point Ar | very low MP/BP |
why does argon have a low melting/boiling point | monoatomic- very weak VDWs between atoms |