Topic 1-5 Flashcards
How did Melendeev arrange the elements?
- arranged the elements known at the time in a periodic table
- by using properties of these elements and their compounds
- also used this table to predict the existence and properties of some non discovered elements
How did Mendeleev predict era-aluminium would be a metal?
When gallium was discovered it’s properties closely fitted those he had predicted for Eka-aluminium
Describe the atomic structure
Has a nucleus that contains protons and neutrons surrounded by electrons in shells
Reason why atoms are neutral
Atoms contain the same number of protons and electrons so negative and positive charges cancel out
What’s is the mass number ?
Total number of protons and neutrons
What is the atomic number ?
Number of protons and electrons
Describe arrangement of elements
- Arranged in order of increasing atomic number arranged in periods
- Elements with similar properties are placed in the same vertical column called groups
What is an isotope ? And what Is the result of its existence?
- different atoms of an element with the same atomic number but different amount of neutrons
- results in relative atomic mass not being a whole number
What is the connection between increasing shells and placement in periodic table?
The more shells it has the more reactive the element is because inner electrons repel the outer electrons
What’s is formed when atoms of different elements combine?
A compound is formed by forming new chemical bonds
How are ionic bonds formed?
By transfer of electrons to produce cations and anions
Difference between a cation and anion
Cation
-metal atoms that lose electrons to form positively charged ions
Anion
-non metal atoms that gain electrons to form negatively charged ions
What is an exothermic reaction ?
A reaction which heat is released in forming bonds in the product is GREATER than energy needed to break bonds in the reactant
Collision theory
Increase temperature, surface area,concentration and add catalyst the frequency of successful collisions is greater
What happens when a metal reacts with a non metal to form a compound ?
- Electrons are transferred from metal atoms to non metal atoms
- this forms a positive charge for the metal ion and a negative charge for the non metal ion because it gains a negative charge
- oppositely charged ions attract each other strongly the new chemical bond formed is ionic
What charge is group 1,2,3,4,5,6,7,8
Group 1 1+ Group 2 2+ Group 3 3+ Group 4 -- Group 5 3- Group 6 2- Group 7 1- Group 8 0 - are inhert
What is an ion ?
A charged particle either negative or positive
What is the difference in compound endings ?
ide
No oxygen present
ate
Oxygen is present
Describe structure of ionic compounds as Lattice structures
- Ionic compounds as a lattice structure consists of regular arrangement of ions
- held together by strong electrostatic forces between oppositely charged ions
Name 5 compounds and their charge
Hydroxide OH- 1- Nitrate NO3 1- Oxide O2- 2- Carbonate CO3 2- Sulfate SO4 2-
Explain and describe properties of ionic substances
- *HIGH MELTING AND BOILING POINT this means they are solids at room temperature
- *ABILITY TO CONDUCT ELECTRICITY when molten or in aqueous solution
- *STRONG because energy is required to break the ionic bond and there is many of them in an ionic compound
Conditions for an ionic substance to conduct electricity
-substance must contain free to move charged particles (electrons)
**
Ionic compounds contain charged particles in a solid form ions are held in fixed position forming a lattice structure in which they can vibrate but are o free to move when molten or in aqueous solution
Under what conditions will a soluble conduct electricity
A soluble (e.g. NaCl) will dissolve in water and will conduct electricity under aqueous conditions
Under what conditions will a insoluble conduct electricity
An insoluble (e.g. MgO) does not dissolve at all in liquids , solids only conduct electricity when heated till molten
Suggest why magnesium oxide is used to line inside blast furnaces ?
MgO is a REFRACTORY material meaning it is RESISTANT TO HEAT
because it has high melting point because of the strong ionic bonds between magnesium (2+)and oxygen (2-)ions
Name the common substances soluble in water
(1. )Sodium potassium and sodium ammonium salts
(2. )All nitrates
(3. )common chlorides
(4. )common sulfates
(5. ) sodium carbonate , potassium carbonate, ammonium carbonate
(6. )sodium hydroxide, potassium hydroxide, ammonium hydroxide
List common types of insoluble substances in water
(1. ) silver chloride , lead chloride
(2. ) lead sulfate, barium sulfate , calcium sulfate
(3. ) rest of carbonates not listed in soluble
(4. ) most hydroxides not listed in soluble