Chapter 3 - Periodic Table Flashcards
How and when developed the first periodic table ?
Dmitri Mendeleev in 1896
What were the features of Mendeleev’s periodic table ?
- left gaps for undiscovered elements
- listed the elements in increasing atomic weight
How do todays periodic table differ from Mendeleev’s ?
- Mendeleev’s had no noble gases
- gaps were left in his
- no block of transition metals in Mendeleev’s
- actinides and lanthanides not present in Mendeleev’s
What does the staircase line on the periodic table separate ?
The metals and the non-metals
What two elements are liquids and describe their appearance .
Bromine: red-brown liquid
Mercury: silvery-white liquid
What is a group ?
A group is a vertical column in the periodic table
What do all elements in the same group have in common ?
- similar chemical properties
- same number of electrons in their outer shell
What is the name of group 1 ?
alkali metals , reactive
What is the name of group 2 ?
alkaline earth metals , reactive
What is the name of group 7 ?
Halogens, reactive
What is the name of group 8 ?
noble gases, unreactive
What is a period ?
A period is a horizontal row in the periodic table
What are the physical properties of group 1 metals ?
- soft
- shiny
- low density
- grey solids
- low melting points
What is the equation shown when a group 1 metal reacts with water ?
Group 1 metal + water —-> metal hydroxide + hydrogen
What are the risk assessments when using group 1 metals ?
- use tweezers
- use a safety screen
- wear safety glasses
- use small pieces of metal
What are the observations when lithium reacts with water ?
- moves on surface
- bubbles
- heat released
- disappears
What are the observations when sodium reacts with water ?
- moves on surface
- bubbles
- heat released
- disappears
What are the observations when potassium reacts with water ?
- lilac flame
- moves on surface
- bubbles
- heat released
- disappears quickly
- crackles at end
What is the general half equation for a group one metal reaction ?
Group 1 metal atom —-> Group 1 metal ion + electron
Why does the reactivity of group 1 metals increase as you go down the group ?
The atom they need to lose becomes further away from the nucleus and is therefore easier to lose.
What are the physical properties of the halogens ?
Fluorine : yellow gas Chlorine: yellow-green gas Bromine: red-brown liquid Iodine: grey-black solid Astatine : - -
What is the trend of the halogens as they go down the group ?
- elements become darker
- change from a gas to liquid to solid
- increase in melting point
Explain toxicity regarding the halogens.
All the halogens are toxic, although toxicity decreases down the group.
What is sublimation ?
sublimation is the change of state from solid directly to gas on heating.
