Chapter 10: Periodicity Flashcards
Why does the atomic radii decrease across a period?
The number of electron shells stay the same.
The protons/nuclear charge increases, so the electrostatic force increases and the protons pulls the electrons closer.
Which element has the highest melting point in period 3?
Silicon
What is the trend of melting points in period three?
Increase in melting point until silicon, then significant decrease after, (with sulfur having a higher melting point then phosphorus)
What is the trend of electrical conductivity in period 3?
Decrease electrical conductivity. Last two elements (Cl and Ar) have 0 electrical conductivity.
Which element in period 3 has a giant molecular structure?
Silicon, (the rest is giant metallic or simple molecular)
What is the formula of a simple molecule of sulphur?
S8
What is the formula of a simple molecule of phosphorus?
P4
What period 3 chloride doesn’t react with water?
Magnesium
Why doesn’t silicon oxide react with water?
Because it has a giant molecular structure
What are the conditions needed for silicon to react with oxygen?
Powdered Si and heat strongly
What is the flame colour of sodium?
Bright yellow
What is the flame colour of magnesium?
Bright white
What is aluminum flame colour?
Bright white
What is the flame colour of silicon?
Bright white sparkles
What is the flame colour of phosphorus?
yellow or white flame
What is the flame colour of sulphur?
Blue flame
What is the product of sulphur’s reaction with oxygen
sulfur dioxide that is shown as toxic fumes
What are the reaction conditions needed for phosphorus?
Heat and excess chlorine
Which period three elements react slowly with chlorine?
Silicon and phosphorus.
Describe sodium’s reaction with cold water.
It reacts vigorously with cold water.
It melts into a ball, and dissolves completely
hydrogen is given off
strong alkaline solution (PH14) formed.
Describe magnesium’s reaction with cold water and hot.
It reacts extremely slowly with cold water, forming PH 11 solution, since magnesium hydroxide is only slightly soluble. But it reacts vigorously with steam.
Which oxides are insoluble in water?
Aluminum and silicon
What colour of flame is produced when sodium reacts with chlorine?
Bright orange
What colour of flame is produced when magnesium reacts with chlorine?
Bright white
What is observed when aluminum reacts with chlorine?
Pale yellow aluminum chloride is produced
What is the molecular formula of aluminum chloride?
Al2Cl6
What is produced when silicon dioxide reacts with sodium hydroxide?
sodium silicate (Na2SiO3) and water
What is the product produced when aluminum chloride reacts with water?
[Al(H20)6]3+ and chlorine ions
What is observed when chlorine is produced?
Misty fumes
Which period 3 chloride can conduct electricity when it is added to water but not when it is in its liquid state?
Phosphorus and silicon
