Periodic Tables + Trends

• Non-metals


  Gain electrons to become anions with the electron configuration of the next noble gas
• Group 1: Silver, soft metals, low density, easily react with water and halogens. Reactivity increases down the group. Alkali Metals
• Metallic and non-metallic behaviours of elements

  Including group trends and reactivity for alkali metals (Li–Cs) and halogens (F–I)
• Non-metals within groups

  Reactivity decreases down a group as it is harder for non-metals to attract electrons into valence shells
• Metals across periods

  Reactivity decreases across a period as the increasing nuclear charge makes it more difficult for a metal to lose electrons
• Group 18: Mostly unreactive. Noble Gases
• Metals


  Lose electrons to become cations with the electron configuration of the previous noble gas
• Periods

  Horizontal rows of the periodic table (7)
• Groups

  Vertical columns of the periodic table (18)
• Metals within groups

  Reactivity increases down a group as it is easier for metal with a greater number of shells to lose electrons
• Group numbering scheme from group 1 to group 18, as recommended by IUPAC, should be used
• Structure of the periodic table

  Based on the atomic number and properties of the elements
• Atomic radius


  Size of an atom, measured as the distance between adjacent nuclei
• Group 17: Diatomic molecules, highly reactive with alkali metals, harmful or lethal to the environment. Decrease in reactivity down the group. Halogens
• Elements

  Type of atom defined by its atomic number
• Metallic character

  Ease with which an atom loses electrons
• Group 2: Slightly higher density, react slowly with water. Alkaline Earth Metals
• Periodic Table

  • Elements organized in ascending order of atomic number to emphasize the regular repetition of chemical and physical properties
• Atomic radius decreases from le
• Transition Metals

  • Groups 3 – 12, form colourful compounds, specify with a Roman numeral after the metal to denote charge and oxidation state of the transition metal ion
• Non-metals across periods


  Reactivity increases across the period as the increasing effective nuclear charge makes it easier for a non-metallic atom
• Negative ions are larger than the neutral atoms because they have gained space-occupying electrons
• Describe and explain that elements of the periodic table show trends across periods and down groups, including atomic radii, valencies, ionic radii, 1st ionisation energy, and electronegativities as exemplified by groups 1, 2, 13–18 and period 3
• With each increase in atomic number, there is an increase in the number of positively charged protons so the electrostatic attraction from the protons pulls the electrons closer and the atomic radius gets slightly smaller
• Atomic Radii

  • Smallest atomic radius in any period is that of the noble gas, and the largest is that of the alkali metal
• Analyse, evaluate, and interpret data to explain and justify conclusions for periodic trends, patterns, and relationships
• With each energy level that is added to an atom, there are more electrons that need to occupy space, so the atom increases in size
• Positive ions are smaller than the neutral atoms because they have lost space-occupying electrons
• Identify the elements that demonstrate a spike in the graph. What is similar about them?
• Elements in the same period

  As you move across the periodic table, the trend is decreasing atomic radii. This occurs due to the increase in the number of positively charged protons, pulling the electrons closer
• Atomic Radii

  1. Decreases from left to right across a period because of electrostatic attractions

  2. Increases down a group because of the electron shielding effect
• Valency

  1. Valence electrons are the electrons occupying the outermost energy level of an atom

  2. Related to the electron configuration of their atoms

  3. Normally written as the charge of the ion once the atom has gained or lost electrons to have a noble gas electron configuration

  4. Transition metals can show more than one valency, often expressed as Roman numerals
• Elements in the same group

  As you move down the periodic table, the trend is increasing valency. This occurs because of the addition of energy levels, leading to more electrons in the outer shell
• Ionic Radii

  1. Positive ions are smaller than the neutral atoms because they have lost space-occupying electrons

  2. Negative ions are larger than the neutral atoms because they have gained space-occupying electrons
• Ionisation Energy trends across a period

  Increases across a period. Increase in electrostatic attraction makes it harder to remove electrons
• Electronegativity trends across a period

  Increases across a period. Outer valence shell is closer to the nucleus, so electrons more strongly attracted to nucleus
• Nature of oxides across a period

  Ionic bond forms between atoms with large difference in electronegativity. Electronegativity increases from left to right
• Electronegativity trends down a group

  Decreases down a group. Size of atoms increases, so outermost electrons are further from nucleus and the electrons are less strongly attracted
• In each case, the large increase in ionization energy occurs because an electron is being pulled from an inner shell which is closer to the nucleus and also because it is coming from a more stable shell
• If the atom the OH bonds to is highly electronegative

  The oxide formed will be acidic