Atomic Structure and the Periodic Table Flashcards
What determines the size of an atom?
Volume of electron’s orbits
What is radius of an atom?
0.1 nano meters
What is the charge of the nucleus and why?
Positive charge because protons
What does the nucleus contain?
Contains protons and neutrons
Where is almost the whole mass of atom is concentrated?
In nucleus
What is no. of protons equal to?
no. of electrons
What does the nuclear symbol of atom (i.e. what’s on the periodic table) tell you?
Its atomic number and mass number
What a mass number?
Total number of protons and neutrons in atom
What’s the atomic number?
Number of protons
How do find the no. of neutrons?
Mass Number − Atomic Number
What is the name given to substances that only contains atoms with same number of protons?
Elements
Define isotopes
Different forms of same element, which have same no. of protons, but different no. of neutrons
What is relative atomic mass?
Average mass of one atom of an element (including
isotopes)
How are elements laid out in the periodic table?
In order of increasing atomic (proton) number
Where are metals & non-metals on the periodic table?
Metals are on left and non-metals on right
What does the group number tell you?
Number of electrons in outer shell
Exception Group 0 which has Helium (2 electrons)
What do periods show you?
New period = another full shell of electrons
What does having one electron on the outer shell do to an atom?
Makes them very reactive and gives similar properties
Name 2 properties of Group 1 metals
All are soft and have low density
As you go down Group 1…. (Name 3 things)
- Increasing reactivity
- Lower melting points
- Lower boiling points
(4. Higher relative atomic mass)
Why does reactivity increase as you go down Group 1?
- Outer shell electron is further away from nucleus, further down the group
- ∴ attraction between nucleus and electron decreases
- Outer electron is more easily lost
What do alkali metals form with non-metals & why?
Ionic compounds with charge go +1 - don’t need much energy to remove 1 outer electron to form full outer shell
What are ionic compounds formed from alkali metals and non-metals like?
Usually white solids that dissolve in water to form colourless solutions
Name 3 observations that occur when alkali metals react with water
- Metal travel quickly along surface of water
- Lots of fizzing
- Metal gets smaller
- Universal indicator turns purple
Why does universal indicator turn purple when alkali metals react with water?
Salts produced dissolve in water to produce alkaline solutions
Name 2 properties of Group 7 elements
All Non-Metals with Coloured Vapours
What structures do halogen compounds have?
Simple molecular (covalent) structures
As you go down Group 7, halogens… (name 3 things)
- Become less reactive
- Have higher melting and boiling points
- Have higher relative atomic masses
Why does the reactivity decrease as you go down Group 7?
Harder to gain extra electron = outer shell’s further from nucleus
Name 2 properties of Group 0 elements
All Inert, Colourless Gases (at room temp)
Why are noble gases non-flammable?
Bc they’re inert
What do noble gases exist as?
Exist as monatomic gases (single atoms not bonded to each other)
As you go down group 0…
Boiling points of noble gases increase
Why does the boiling point of noble gases increase as you go down the group (0)?
Bc there’s increase in no. of electrons in each atom = greater intermolecular forces between them which need to be overcome
Who developed the periodic table?
Dmitri Mendeleev
What did Dmitri Mendeleev do to the periodic table?
Left gaps and predicted new elements
What was the order of Mendeleev’s periodic table?
Elements mainly in order of atomic mass but switched some to group that had other elements with similar properties
What did the gaps in Mendeleev’s periodic table ensure?
Elements with similar properties stayed in same groups
Why were their gaps in Mendeleev’s periodic table and what did this allow him to do?
Gaps indicated existence of undiscovered elements & allow him to predict what properties they may have
Where are the transition metals located in the periodic table?
In centre of periodic table between group 2 and group 3
Name 3 special properties of transition metals
- Can have more than one ion
- Compounds formed are colourful
- Make good catalysts
Why are compounds formed with transition metals colourful?
Transition metal ions = often coloured
Give an example of a transition metal used as a catalyst in a named process
Iron catalyst used in Haber process
Describe how properties of transition metals differ compared to the properties of group 1 metals (name 3 properties)
- Have higher melting points (expect for mercury) + higher densities
- Much less reactive
- Are stronger and harder
When alkali metals react with water, what do they release?
Hydrogen
What do alkali metals form and what kind of solutions do they give when dissolved in water?
Form hydroxides that dissolve in water to give alkaline solutions
Explain why fluorine is the most reactive element in Group 7
- Fewest energy levels in group 7
- Greatest attraction between nucleus and outer shell
- ∴ fluorine can gain an electron in its outer shell more easily
