ATOMIC STRUCTURE & THE PERIODIC TABLE
What are the three main subatomic particles found in atoms?
Protons, neutrons and electrons.
What type of bonding involves atoms sharing electrons?
Covalent bonding.
What is the difference between speed and velocity?
Speed is distance travelled per unit time; velocity is speed in a specified direction.
What is the SI unit of energy?
Joule (J)
What is density?
Mass per unit volume.
hat are the vertical columns in the periodic table called?
Groups
What type of bonding occurs between oppositely charged species?
Ionic bonding.
A car travels at a constant velocity of 15 m/s. What is its acceleration?
0 m/s², because its velocity is not changing.
A moving object has which type of energy store?
Kinetic energy.
An object has a mass of 600 g and a volume of 200 cm³. What is its density?
m (g) / v (cm3) = ⍴ (g/cm3)
600 / 200 = 3 g/cm3
The number of which subatomic particle determines which element an atom is?
The number of protons in its nucleus.
A chemical reaction releases heat energy into its surroundings. What adjective describes this type of reaction?
Exothermic.
A cyclist accelerates from 4 m/s to 16 m/s in 6 seconds. Calculate the acceleration.
(16 m/s - 4 m/s) / 6 s =
12 / 6 = 2
2 m/s2
A student lifts a 10 kg box vertically upwards by 2 m. What is the change in gravitational potential energy?
GPE (J) = 10 kg x 10 N/kg x 2
GPE = 200 J
What happens to pressure if the contact area between two surfaces is reduced while the force remains the same?
Pressure increases.
An atom contains 17 protons, 18 neutrons and 17 electrons. What element is it, and what is its mass number?
Chlorine; mass number = 17 + 18 = 35.
Magnesium forms Mg²⁺ ions and chlorine forms Cl⁻ ions. What is the formula of magnesium chloride?
MgCl₂
A 1,200 kg car experiences a resultant force of 3,600 N. Calculate its acceleration.
F / m = a
3600 N / 1200 kg = a
3 m/s2 = a
A machine receives 500 J of energy and produces 350 J of useful energy. Calculate its percentage efficiency.
(350 J / 500 J) x 100 =
0.7 x 100 = 70 %
A metal cube has a mass of 2 kg and a volume of 0.0005 m³. Calculate its density in kg/m³.
2 kg / 0.0005 m3 = ⍴ (kg/m3)
2 / 5/10,000 =
2 x 10,000 / 5 =
20,000 / 5 = 4,000 kg/m3
An atom of sodium has 11 protons but loses one electron. What charge does the resulting ion have, and why?
+1, because it has 11 protons but only 10 electrons, giving one more positive charge than negative charge.
Balance this equation:
H₂ + O₂ → H₂O
2H₂ + O₂ → 2H₂O.
A car travels at 20 m/s. The driver brakes and the car comes to rest in 5 seconds. What is its acceleration?
(0 m/s - 20 m/s) / 5 s = a
-20 / 5 = - 4 m/s2
A 2 kg block of aluminium is heated from 20°C to 70°C. Its specific heat capacity is 900 J/kg°C. Calculate the thermal energy transferred to it.
Q = mcΔT
Q = 2 kg x 900 J/kg°C x (70-50)
Q = 2 x 900 x 50
Q = 90,000 J
A diver is 10 m below the surface of water. The density of water is 1,000 kg/m³ and g = 10 N/kg. What is the pressure due to the water?
100,000 Pa (100 kPa).