Module 3.1
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Give an outline of the periodic table
• Consists of rows (periods- horizontally across) • Consists of groups • Arranged by increasing atomic number
In the periodic table, elements are arranged by …
Increase atomic number
What groups are fond in the s block?
Groups 1 and 2
What groups are found in the p block?
Groups 3-8
What are the names of the elements found in block d?
Transition metals
Define the term periodicity
Trends that occur in physical and chemical properties as we move across the periods of the periodict table
When talking about periodicity, list 5 different trends that we talk about
• Ionisation energy • Melting Points/Boiling Points • Reactivity • Atomic Radius • Electronegativity
Do all the elements within a group have similar reactions, why?
Elements in the same group have the same number of electrons on their outer shell. Therefore, they have similar chemical properties.
What was Döbereiner’s theory about?
Triads
What was John Newlands’ theory about?
Law of octaves
What was Mendeleev’s theory about?
Gaps, elements arranged in order of increase atomic mass
What is the modern day theory of the periodic table?
Elements are arranged in order of increasing atomic number
Explain Döbereiner’s theory behind his model of the periodic table
• Döbereiner grouped similar elements in TRIADS e.g. Li,Na and K. • He ordered elements by atomic mass. • The middle element in his triads had SIMILAR properties to the other TWO elements.
Explain John Newlands’ theory behind his model of the periodic table
• Newlands arranged elements in order of mass. He noticed that every 8th element was SIMILAR.
Explain Mendeleev’s theory behind his model of the periodic table
• He arranged all known elements by atomic mass • He left GAPS, where no element fitted the repeating patterns • Predicted the patterns of missing elements
Explain the theory behind the modern day periodic table ( Henry Moseley)
• Elements are arranged by increasing atomic number - There are groups and periods
Define first ionisation energy
The amount of energy needed to remove 1 mole of electrons from 1 mole of gaseous atoms.
Give the equation for the first ionisation energy of oxygen
O(g) → O^+ (g) + e^-
Give the equation for the first ionisation energy of magnesium
Mg(g) → Mg^+ (g) + e^-
Give the equation for the first ionisation energy of Sodium
Na(g) → Na^+ (g) + e^-
When talking about first ionisation energy what must you include?
• Charges • Gaseous state • The amount of energy needed to remove 1 mole of electrons from 1 mole of gaseous atoms
The lower the ionisation energy, the easier/harder it is to form an ion?
Easier
What factors affect ionisation energy?
Nuclear charge Atomic radius Shielding
How does nuclear charge affect ionisation energy?
The higher the nuclear charge, the larger the electrostatic attraction between the nucleus and the outermost electrons. Therefore, more energy is required to remove 1 mole of electrons from 1 mole of gaseous atoms, so the as nuclear charge increase, so does IE. Higher nuclear charge = Higher Ionisation energy