🧬 CATEGORY 1: Periodic Trends
What happens to atomic radius as you move down a group?
It increases.
Name three properties of metals.
Shiny, malleable, conductive.
What are the three subatomic particles?
Protons, neutrons, electrons.
What is the formula for density?
Density = Mass ÷ Volume.
What does it mean when an element is “reactive”?
It easily combines or changes when interacting with other substances.
What happens to electronegativity as you move across a period?
It increases.
What makes metalloids unique?
They have both metallic and nonmetallic properties.
What does the atomic number represent?
The number of protons.
An object with mass 50 g and volume 25 mL has what density?
2 g/mL.
Which group of metals is the most reactive?
Group 1 — Alkali metals.
Which element is larger: Li or Cs and why?
Cs; more energy levels = larger radius.
What property was tested in your Metals Lab that shows if energy can flow through a substance?
Conductivity.
What happens when a neutral atom gains an electron?
It becomes a negative ion (anion).
What happens to the volume of water when you place a dense object inside it?
The water level rises (displacement).
Which group of nonmetals is the most reactive?
Group 17 — Halogens.
Which has a higher electronegativity energy: O or N?
O; smaller radius = electrons held more tightly.
Why are nonmetals poor conductors?
They hold their electrons tightly.
How many valence electrons does chlorine have, and what ion will it form?
7 valence electrons → gains 1 → Cl⁻.
Why does ice float in water?
It’s less dense than liquid water.
Why are noble gases the least reactive?
They already have full outer shells.
Explain the connection between radius and reactivity in metals.
Larger radius → weaker attraction → more reactive.
Based on your lab, explain how metals and nonmetals work together in a power cord.
Metal core conducts; nonmetal coating insulates.
Explain how a Bohr model helps you predict an element’s reactivity.
Shows how close the atom is to a full outer shell.
Two blocks have equal mass but different volumes. Which is denser?
The one with smaller volume.
Compare the reactivity of lithium (Li) and rubidium (Rb). Which is more reactive and why?
Rb; lower electronegativity and larger radius make it easier to lose electrons.