Section 2-The Periodic Table and Bonding P1 Flashcards
What is the periodic table?
The Periodic Table is a table of all known elements.
-Dmitri Mendeleev ordered the elements by atomic mass to make a table of elements
How is the periodic table arranged?
-its laid out in columns (groups) and rows (periods)
What are the features of groups?
- have similar properties
- group number corresponds to the number of electrons in its outer most shell
What are the features of periods?
-determines the number of shells an element will have
What are the special names for?
Group 1 elements:
Group 7 elements:
Group 0/8 elements:
Group 1 = alkali metals
Group 7 = halogens
group 0/8 = noble gases
How was the periodic table made?
The periodic table was made by looking at the properties of the elements and arranging them into groups, the same groups that they have today.
What does the properties of elements depend on?
The properties depend on the number of electrons
- atomic number is therefore significant because it equals the number of electrons
- the number of electrons in the outer most shell is the most important for chemical properties
What are the electron shell rules:
- electrons always occupy shells, always building from inside out
- 1st shell has 2 electrons, 2nd and 3rd shell have 8 electrons
- atoms always try to have full outer shells, but in most atoms the outer shell isn’t full so they want to react to get a full outer shell
How do you work out electronic configurations?
- find out the atomic number
- start from the inner most shell and fill the with 2 from the atomic number and then carry on for as many electrons you have, adding another shell every 8
How do you draw electronic configurations?
- each circle you surround the nucleus with represents an energy shell and then on each shell you fill it with the number of electrons for that energy level
- represent electrons with crosses
How do you work out the electronic configuration from its period and group?
- period- tells you the number of shells
- group- tells you the number of electrons in the outermost shell
On the periodic table where is the split between metals and non metals?
REMEBER Al-Po B-At
-to the right there is non-metals to the left there is metals
What are general property rules about metals?
- conduct electricity
- metal oxides are basic (they will neutralise acids, they are alkaline)
What are the general property rules for non-metals?
- poor conductors of electricity
- non-metal oxides are acidic (they will neutralise bases, they are acids)
what are the properties on noble gases and why do they have these properties?
-they are inert (very unreactive), because they have a full outer shell so they don’t need to gain or loose electrons (they are stable)
Define ions:
Ions are charged particles (they can be single atoms or groups of atoms)
Why do atoms gain or loose electrons to form ions?
To get a full outer shell
-atoms with full outer shells are stable
Chemical formula for Silver: (and charge)
Ag (charge +)
Chemical formula for Iron(II): (and charge)
Fe (charge 2+)
Chemical formula for Copper: (and charge)
Cu (charge 2+)
Chemical formula for Iron(III): (and charge)
Fe (charge 3+)
Chemical formula for Lead: (and charge)
Pb (charge 2+)
Chemical formula for Zinc: (and charge)
Zn (charge 2+)
Chemical formula for Hydrogen: (and charge)
H (charge +)
Chemical formula for Hydroxide: (and charge)
OH (charge -)
Chemical formula for Ammonium: (and charge)
NH₄ (charge +)
Chemical formula for Carbonate: (and charge)
CO₃ (charge 2-)
Chemical formula for Nitrate: (and charge)
NO₃ (charge -)
Chemical formula for Sulfate: (and charge)
SO₄ (charge 2-)
What is ionic bonding between?
A non-metal and a metal
Describe ionic bonding:
The oppositely charge ions are strongly attracted to each other(electrostatic attractions)
- the non-metal loses electrons(forms a positive ion)
- the metal gains electrons(forms a negative ion)
What is the overall charge of an ionic compound:
zero
-all charges must be balance in an ionic compound
How do you draw a diagram to represent an ionic compound?
- draw each atom separately, with dots and crosses representing the electrons
- then draw an arrow and draw the atoms again but this time with the appropriate full outer shell
- put brackets round the ions and label the charge outside of the brackets
Describe the structure of an ionic compound:
- giant ionic structures
- ions are held together in a closely packed lattice
- very strong electrostatic attraction
Describe the characteristics of an ionic compound:
- very strong electrostatic attraction (so requires a lot of energy to break the bonds - have high melting and boiling points)
- not electrical conductors as a solid
- when molten they are electrical conductors (because the electrons are free to move)
What is covalent bonding?
- Covalent bonding is when atoms bond together by sharing electrons with other atoms
- Each covalent bond provides one extra shared electron for each atom
Why do atoms bond covalently?
- to feel like they have a full outer shell (makes them stable)
- strong electrostatic attraction between the negatively charged shared electrons and the positively charged nuclei of the atoms involved
What is the bonding in Hydrogen?
COVALENT - H₂
-single covalent bond
What is the bonding in Chlorine?
COVALENT - Cl₂
-single covalent bond
What is the bonding in Hydrogen Chloride?
COVALENT - HCl
-single covalent bond
What is the bonding in Ammonia?
COVALENT - NH₃
-made up of three single covalent bonds
What is the bonding in Nitrogen?
COVALENT - N₂
-one triple covalent bond
What is the bonding in Water?
COVALENT - H₂O
-two single covalent bonds
What is the bonding in Oxygen?
COVALENT - O₂
-one double covalent bond
What is the bonding in Carbon Dioxide?
COVALENT - CO₂
-two double covalent bonds
What is the bonding in Methane?
COVALENT - CH₄
-four single covalent bonds
What is the bonding in Ethane?
COVALENT - C₂H₆
-the carbons have one single bond between them and have 3 hydrogen’s each
What is the bonding in Chloromethane?
COVALENT - CH₃Cl
-four single covalent bonds, one to each hydrogen and chlorine from the carbon
What is the bonding in Ethene?
COVALENT - C₂H₄
-one double covalent bond between the carbons and 4 single covalent bonds between the carbons and hydrogens
Define a covalent bond:
The electrostatic attraction between a pair of electrons and the nuclei of two atoms
Examples of: Giant covalent structures?
All from carbon Also known as macro molecules -diamond -graphite -fullerenes
Properties of diamond?
Carbon
- all 4 outer electrons Form covalent bonds
- 3D structure formed
- each carbon atoms forms 4 bonds to other carbon atoms
- no weak intermolecular forces
- very high melting point
- very hard and abrasive
- doesn’t conduct electricity
- used for cutting tools and diamonds
What are the properties of giant covalent structures?
- all the atoms are bonded together by strong covalent bonds
- lots of strong covalent bonds -> lot of energy to break them -> high melting and boiling points
- don’t conduct electricity (except for graphite when molten)
- usually insoluble in water
- made of carbon
Properties of graphite?
Carbon
- 3 outer electrons used to form covalent bonds(the fourth becomes a delocalised electron)
- layered structure formed
- weak intermolecular forces between the layers
- high melting point
- soft and slippery
- conducts electricity(because of the delocalised electron)
- used lubricant, pencils
What are the properties of simple molecular substances?
- the atoms within a molecule are held together by strong covalent bonds but between the molecules there are weak intermolecular forces
- low melting and boiling points, easily separated
- liquid or gas a room temperature generally
- don’t conduct electricity
- insoluble in water but soluble in organic solvents
As the Mr (relative atomic mass) of a substance increases what happens to the intermolecular forces between the molecules?
As the Mr increases the intermolecular forces become stronger because more energy is needed to the intermolecular forces because there are more of them
-melting and boiling points of simple molecular substances increases as the Mr does
Properties of Fullerene?
C₆₀ is a simple molecular substance
- hollow sphere structure
- made up of large covalent molecules
- Fullerene molecules are held together by intermolecular forces so they can slide over each other
- has one delocalised electron but it can’t move between the molecules so it’s a poor conductor of electricity