Y9 EOY Science test (Chemistry)

What is everything made up of?

Atoms

Structure of an atom

Radius of an atom

0.1nm

Radius of a nucleus (in an atom)

Around 1/10000 the radius of an atom

Relative mass of a proton

1

Relative charge of a proton

+1

Relative mass of a neutron

1

Relative charge of a neutron

0

Relative mass of an electron

5.4 × 10(to the power of -4)

Relative charge of an electron

-1

What is the charge of an atom and why?

Atoms have a neutral charge because they have an equal number of protons and electrons

What is an element?

An element is a substance made of one type of atom

Atoms of an element have the _____ number of protons. Atoms of different elements have a ______ number of protons

1.same

2.different

Relative atomic mass of an element

The average mass all of the isotopes of the element

State how many different types of elements there are

Around 100

Compound

Made of atoms of different elements that are chemically bonded to each other

Which of these formulas are a compound:

.H₂O or S?

H₂O

What is needed to separate compounds back into elements?

A chemical reaction

What is a molecule made up of?

Atoms chemically bonded to each other

Made of atoms of different elements that are chemically bonded to each other

Compound

Atoms chemically bonded to each other

What is a molecule made up of?

What are made during chemical reactions?

New substances

Conversation of mass

mass of products = mass of reactants

How is an ion formed?

When an atom loses or gains an electron

Metal ions become…

Positive ions

Non-metal ions become…

Negative ions

Charge of ions in Group 1

Positive

Charge of ions in Group 2

Positive

Charge of ions in Group 6

Negative

Charge of ions in Group 7

Negative

Before the discovery of the electron, what did scientists think atoms were?

Solid spheres

Isotopes

Atoms with the same number of protons but a different number of neutrons

How do you calculate the relative atomic mass of an element?

total mass of atoms/ total number of atoms (and need some example questions)

There are two isotopes of chlorine, ³⁵Cl and ³⁷Cl. 75% of all chlorine atoms are ³⁵C and the remaining 25% are ³⁷Cl. Find the relative atomic mass of chlorine.

Cl - 35 = 75%

Cl - 37 = 25%

Average mass = total mass of atoms/ total number of atoms

Average mass = (35 × 75) + (37 × 25) / 75 + 25

Average mass = 2625 + 925 / 100

Average mass = 3550 / 100

Average mass = 35.5

There are two isotopes of boron, ¹⁰B and ¹¹B. 20% of all chlorine atoms are ¹⁰B and the remaining 80% are ¹¹B. Find the relative atomic mass of boron rounded to the nearest whole.

B - 10 = 20%

B - 11 = 80%

Average mass = total mass of atoms/ total number of atoms

Average mass = (10 × 20) + (11 × 80) / 20 + 80

Average mass = 200 + 880 / 100

Average mass = 1080 / 100

Average mass = 10.8

= 11 (Rounded to the nearest whole)

There are two isotopes of neon, ²⁰Ne and ²²Ne. 90% of all neon atoms are ²⁰Ne and the remaining 10% are ²²Ne. Find the relative atomic mass of neon to the nearest whole.

Ne - 20 = 90%

Ne - 22 = 10%

Average mass = total mass of atoms/ total number of atoms

Average mass = (20 × 90) + (22 × 10) / 90 + 10

Average mass = 1800 + 220 / 100

Average mass = 2020 / 100

Average mass = 20.2

= 20 (Rounded to the nearest whole)

What is the plum pudding model?

A model made by Thomson which had the atom as a ball of positive charge with electrons randomly embedded in it

Why was the plum pudding model proposed?

Because the electron was just discovered

Explain how the results from Rutherford scattering experiments disproved the plum pudding model

Unlike the plum pudding model, electrons orbit around the nucleus

What is the nuclear model?

A model made by Rutherford which had a very small, charged nucleus at the atom’s centre. Electrons orbit the nucleus and the atom is shown to be mostly empty space

Describe the differences between the plum pudding model and the nuclear model in terms of the arrangement of the subatomic particles (4)

.Plum pudding model has no nucleus but the nuclear model does

.Plum pudding model has electrons randomly scattered around but electrons orbit the nucleus in the nuclear model

.Plum pudding model has no protons but the nuclear model does

.Plum pudding model has no neutrons but the nuclear model does

.The positive charge in the plum pudding model is spread out but the positive charge remains in the nucleus in the nuclear model

What does Bohr’s model have?

Electrons orbiting the nucleus in shells

What needs to happen in order for a reaction to take place?

Reacting particles must collide with enough/sufficient energy

What increases the ROR?

.Increasing the temperature

.Increasing the concentration

.Increasing the surface area

.Increasing pressure