ChemistryGrade 9Periodic Classification of Elements

Periodic Trends Lab: Elements and Atomic Properties

Select an element by group and period, then compare atomic radius, ionization energy, electronegativity, and metallic character across the periodic table.

SimulationsLab index
Textbook unitPeriodic Classification of ElementsGrade 9 Chemistry Unit 4
Keywordsperiodic table, elements, group, period, atomic radiusMapped to available textbook headings
Practice modeManipulate, measure, explainUse the controls, then read the live evidence

Chemistry ยท Grade 9

Periodic Trends Lab: Reactivity, Bonding, and Element Properties

Select elements, compare real atomic-property values, test Group 1 and Group 17 reactivity, and predict bonding type from table position and electron attraction.

Atomic radiusNa vs Cl
1

Choose two elements in the same period and record how radius changes from left to right.

2

Choose two elements in the same group and record how ionization energy changes from top to bottom.

3

Compare Group 1 or Group 17 elements and explain the reactivity trend.

4

Compare a metal with a nonmetal and predict bonding type and formula evidence.

P1P2P3P412131415161718
Na
SodiumGroup 1, Period 3metal | 1 valence electron
SelectedNaSodium190 pm
CompareClChlorine79 pm
Increases to upper-rightIonization energy, electronegativity
Increases to lower-leftAtomic radius, metallic character
Atomic radius73%
Ionization energy5%
Electronegativity7%
Metallic character100%
Selected reactivityNa: 80%Alkali-metal reactivity rises down the group.
Compare reactivityCl: 66%Halogen reactivity falls down the group.
Bonding predictionIonic bondingNaClElectronegativity difference is 2.23, so electron transfer is favored.
Trends insight

Across Period 3, effective nuclear charge increases. Electrons are pulled closer, so radius usually decreases from left to right. Na is higher than Cl in atomic radius.

Atomic radius190 pm
Ionization energy496 kJ/mol
Electronegativity0.93
Metallic character100%
Valence electrons1
Reactivity model80%

Lab task

Use the presets, table, and comparison meter to record evidence for one across-period trend and one down-group trend.

Observation rule

Across a period, stronger nuclear pull usually lowers radius and raises ionization energy. Down a group, extra shells increase shielding.

Bonding rule

Large electronegativity differences between metals and nonmetals point to ionic bonding. Similar nonmetals usually share electrons covalently.

Mission

What to prove in this lab

  1. Predict how atomic radius changes across periods and down groups.
  2. Compare ionization energy and electronegativity trends using element position.
  3. Explain why metallic character increases toward the lower-left of the periodic table.