Unit 8 - the periodic table Flashcards
How does the periodic table arrange & organize elements?
In order of increasing atomic number.
The elements are organized in vertical columns (groups I-VIII) which determine the number of valence electrons they have (they have similar chemical properties due to this); and horizontal rows (periods 1-7) which determine how many occupied shells they have.
Describe the physical properties of metals + where they are located on the periodic table
Located on the left side of ladder (group I, roup II, transition elements).
All metals have the following physical properties: electrically conductive, malleable (can be hammered or rolled into thin sheets without breaking), ductile (can be drawn out into wires), thermally conductive, lustrous (shiny)
What happens to metallic properties when you go down a group/across a period and why?
Down a group - metallic properties increase because atoms have more occupied shells, which means that the valence electrons are farther from the nucleus, making it easier to lose electrons
Across a period - metallic properties decrease because the nucleus charge increases due to there being more protons, which attracts electrons more, making it harder to lose them (while the distance from the nucleus remains the same)
What are the chemical properties of metals + metal oxides?
Metallic elements lose electrons to form positive ions called cations. They react with non-metals to form ionic compounds.
Metal oxides have a high melting point and are alkaline. Soluble metal oxides form alkaline solutions with water (ph indicator turns blue/purple)
Describe the physical properties of non-metals + where they are located on the periodic table
Located on the right side of the ladder (include 1 element in group 3, 2 in group 4, 3 in group 5, 4 in group 6, 5 in group 7, all in group 8).
Physical properties of most non-metals include: do not conduct electricity or heat (are insulators), low melting points, low densities, many are gas at room temperature, solid non-metals are brittle & weak, dull
What are the chemical properties of non-metals + non-metal oxides?
Non-metals gain electrons to form negative ions (anions). They react with metals to form ionic compounds but also react with other non-metals to form covalent compounds.
Non-metal oxides usually have low melting points and are acidic. Soluble non-metal oxides form acidic solutions with water (ph below 7 turns red)
What is the trend in melting point and density of Alkali metals?
Down the group, the melting point decreases while the density increases.
What are Alkali metals + chemical properties + what are their compounds like?
Metals in the first group, that are soft, have relatively low melting points & low densities. They are the most reactive metals, and their reactivity increases going down the group (more occupied shells means that electrons are further away from nucleus, making it easier to lose them). They have 1 valence electron which they easily lose to form 1+ ions.
They corrode quickly when exposed to air so are stored under oil. Group I compounds are colorless (white) and water soluble.
What happens when an alkali metal reacts with water?
They produce hydrogen and an alkali.
Describe the reactions between water and a. lithium, b. sodium, c. potassium + why can’t rubidium & caesium be shown in school
A. Lithium floated on the water; there was steady fizzing and the lithium soon disappeared. Universal indicator changed from green to purple (ph 11-14)
B. Sodium melted and floated on water; there was rapid fizzing. Sometimes, it catches on fire (yellow flame) and disappears. Universal indicator changed from green to purple (ph 11-14)
C. Potassium melted and floated on water; there was violent fizzing. Always catches fire (lilac flame) and disappears. Sometimes explodes. Universal indicator changed from green to purple (ph 11-14)
Rubidium and Caesium are too reactive and would explode immediately & violently.
What are halogens + how do they exist?
Elements found in the VII group, most of which are non-metals. They all exist in diatomic molecules (molecules with 2 atoms).
What is the trend in melting & boiling points going down group 7?
They increase
State the colour and state (at r.t.) for each of the halogens
Fluorine - pale-yellow gas
Chlorine - green gas
Bromine - red-brown liquid
Iodine - grey solid (deposits directly from gas to solid)
Astatine - black solid (highly radioactive, does not occur naturally)
What are the chemical properties of halogens?
Reactive non-metals, whose reactivity decreases going down group VII (because there are more occupied shells, so valence shell is farther from nucleus, making it harder to gain electrons). Easily gain electron to form 1- ions. Form ionic compounds with metals (halide salts).
What are the colours of a. chlorine water b. bromine water c. iodine solution?
A. Chlorine water - colourless
B. Bromine water - orange
C. Iodine solution - red-brown
Describe an experiment using displacement reactions to show the reactivity of halogens (colors)
A more reactive halogen will displace a less reactive one from a compound.
When chlorine is added to: potassium iodide - turned red-brown; potassium bromide - turned yellow.
When bromine is added to: potassium iodide - red-brown; potassium chlorine -no change (paler yellow due to dilution of bromine water)
When iodine is added to: potassium bromide - no change (paler red-brown due to dilution of iodine solution); potassium chloride - no change (paler red-brown due to dilution of iodine solution))
Write an ionic equation for the reaction of chlorine water and potassium iodide
Balanced symbol formula: Cl2+2KI -> 2KCl + I2
Ionic equation: Cl2 + 2I(-) -> 2Cl(-) + I2
What are transition elements + physical properties?
Metals between the 2nd and 3rd group. All have typical metallic properties but they have higher melting points and are harder & denser than group I metals. Not all transition metals are magnetic. Zinc is an outlier.
What are 4 chemical properties of transition elements that are different from alkaline metals?
- They are much less reactive than group I or II metals.
- Can have variable oxidation numbers - can form different charged ions. E.g. Fe(ii)O and Fe2(iii)O3
- Transition metal compounds and their solutions are usually colored
- The transition elements and their compounds make good catalysts (substances that speed up reactions without being used up)
What colors are these ions: a. Cu(2+), b. Fe(2+), c. Fe(3+)?
A. Cu(2+) - blue/blue-green
B. Fe(2+) - pale green
C. Fe(3+) - orange-brown
What are noble gases + where are they found?
Colourless, monoatomic (single atom) gases at room temperature in group VIII. All of them are found in small quantities in the atmosphere.
What is the trend for boiling point and density when going down group VIII?
Boiling point and density increases.
What are the chemical properties of noble gases?
They are inert (totally unreactive) as they have a full valence shell (completely stable). They don’t form any chemical compounds.
They can be used to form an inert atmosphere where other gases may react (e.g. light bulbs for lamps)
Why is helium used for airships and balloons instead of hydrogen when both are less dense than air?
Helium is not reactive/flammable because it is a noble gas while hydrogen is flammable (therefore potentially dangerous).
