GR: Atom is electrically neutral.
No. Of + protons inside nucleus equals to No. of - electrons outside nucleus
What is the name of this element? / Write its electronic configuration .
Potassium / K 2, L 8, M 8, N 1
Describe what happens during the heating of solid for a long time.
M. gain T.E, the speed increases, At M.P the I.F weaken, so the I.S increases more and they become more free and the solid melts into liquid
What happens to the K.E when: Increasing the speed of an object to the double and decreasing its mass to half.
K.E is doubled
What is the energy used and produced?
electric or chemical / thermal
This element is:.................../ No. of protons:.............../ No of neutrons:....................
Bromine, 35, 45
G.R: Atoms of inactive elements don't take part in the chemical reaction.
The outermost energy level is completely filled with electrons (they are stable)
GR: No change in the potential energy when the object moves horizontally.
Because the height doesn't change ( = zero), and the P.E is directly proportional to the height
Calculate the mass of an object, its kinetic energy equals 90 J, and its speed equals 6 m.sec.
5 Kg
GR: Water is not used for put out petrol fire.
The D. of petrol is less than water, so it floats on the water surface and the fire keep burning.
We can divided materials according to the hardness into 3 groups: 1.......,2.........,3........
Rubber,Metals, Coal
GR: Cooking pots are made up of aluminium.
Good heat conductor and has high melting point.
GR: Sodium and potassium are kept under kerosene surface.
To protect them from reaction with atmospheric oxygen.
What are examples of inactive metals?
Gold, Silver, Platinum, Nickel.
GR: Metallic spare parts are covered with grease.
To protect them from rust and corrosion.
Complete: ..................solution and....................solution are bad electric conductors.
Sugary solution, hydrogen chloride in benzene.
