P2.5.1 Atomic structure

P2 Physics

KS4 ADDITIONAL SCIENCEMr D Powell

Mr Powell 2012Index

Connection

• Connect your learning to the content of the lesson

• Share the process by which the learning will actually take place

• Explore the outcomes of the learning, emphasising why this will be beneficial for the learner

Demonstration

• Use formative feedback – Assessment for Learning

• Vary the groupings within the classroom for the purpose of learning – individual; pair; group/team; friendship; teacher selected; single sex; mixed sex

• Offer different ways for the students to demonstrate their understanding

• Allow the students to “show off” their learning

Activation

• Construct problem-solving challenges for the students

• Use a multi-sensory approach – VAK• Promote a language of learning to

enable the students to talk about their progress or obstacles to it

• Learning as an active process, so the students aren’t passive receptors

Consolidation

• Structure active reflection on the lesson content and the process of learning

• Seek transfer between “subjects”• Review the learning from this lesson and

preview the learning for the next• Promote ways in which the students will

remember• A “news broadcast” approach to learning

Mr Powell 2012Index

P2.5.1 Atomic Structure

a) The basic structure of an atom is a small central nucleus composed of protons and neutrons surrounded by electrons. (Rutherford Model)

b) The relative masses and relative electric charges of protons, neutrons and electrons.

c) In an atom the number of electrons is equal to the number of protons in the nucleus. The atom has no overall electrical charge.

d) Atoms may lose or gain electrons to form charged particles called ions.

e) The atoms of an element always have the same number of protons, but have a different number of neutrons for each isotope. The total number of protons in an atom is called its atomic number. The total number of protons and neutrons in an atom is called its mass number.

Additional: Candidates should appreciate the relative size of the nucleus compared to the size of the atom.

Mr Powell 2012Index

a) Atomic Model We used to think that atoms weren't made up of smaller pieces. The word "atom" actually comes from a Greek word which means "can't be split up". Now we know that all atoms are actually made of the same 3 tiny particles; protons, electrons and neutrons.

The protons are positive and the electrons are negative. Neutrons are neutral.

Protons and neutrons are much heavier than electrons and they are found in the middle of the atom called the nucleus. The electrons are in orbit around the outside.

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a) & c Atomic Rules - recap

The number of electrons is the same as the number of protons

The number of neutrons is usually about the same as the number of protons though bigger atoms tend to have more neutrons than protons

Atoms have no overall charge.

What are the protons, neutrons, electrons for these three atoms…

Z = number of protons or atomic number or proton number

A = Atomic mass number

Z-A = number of neutrons

3p, 4n, 3e 6p, 6n, 6e 79p, 118n, 79e

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a) Atomic Model Recap S

a) Chargeb) Neutralc) Electronsd) Protonse) Protonsf) Nucleusg) Atomich) Protoni) Nucleonsj) Nucleusk) Massl) Atomic Mass

Word BANK

Nucleus, Mass, Protons, Charge, Proton ,Nucleons, Atomic, Atomic Mass, Protons, Nucleus, Neutral, Electrons

Write a-l in your book and write in the correct order for the words.

B – don’t use the word bank

C-E - Use the word bank to help you

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d) Formation of Ions

When an electron is removed from an atom the overall charge will increase by +1 as an electron is -1 charged

When an electron is added to an atom the overall charge will decrease by -1 as an electron is -1 charged

This example shows the formation of a simple ionic crystal, sodium chloride.

A Chlorine atom steals one from a sodium, forming ions and an attraction strong enough to bond them together.

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a) Rutherford Scattering

In the early part of the last century, the accepted model of the atom was proposed by J J Thompson in his plum pudding model. This consisted of a matrix of protons in which were embedded electrons.

Ernest Rutherford (1871 – 1937) used alpha particles to study the nature of atomic structure with the following apparatus:

Rutherford was using alpha particles (helium nuclei) as nuclear bullets to smash up the atoms; he wanted to see atoms bursting like watermelons. But…

His observations are best illustrated with this video, animation and diagram....

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a) Rutherford Scattering - conclusions

Instead of bits of atom, Rutherford found that a small proportion of the alpha particles were deflected, while an even smaller proportion bounced right back. From analysis of these observations he concluded:

Most of the atom was empty space. The positive charge was concentrated in a very small space The radius of the nucleus was in the order of 3 × 10-14 m. The alpha particles that were deflected back had to be travelling in a line with

the nucleus.

Rutherford’s estimates were not far out. Later research has shown the nuclear radius to be in the order of 1.5 × 10-14 m. However the boundary is not sharp, but rather fuzzy, as the nucleus is a very dynamic entity.

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a) Extended Creative Work!

Imagine that you are team of scientists (3-4) like Ernest Rutherford (1871 - 1937) who have conducted the experiments that we have already talked about.

Produce a short talk of about (1 minute) about the topic which is designed to convince a public in the year 1905 which at that time knew nothing about atoms part from that the universe was made of them. You will have to present it to the rest of the group. Try and speak about;

1) Atoms in general in simple terms. (C)

2) Atoms with specific reference to the electrons, neutrons & protons. (B/C)

3) Ideas of Isotopes. (Y10 work) (B/C)

4) The experiments you conducted (A-C)

5) Main results of your experiments (A*-C)

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Check - Multichoice.... P

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Summary Points…..

The alpha particles that were deflected back had to be travelling in a line with the nucleus.

Most of the atom was empty space.

The positive charge was concentrated in a very small space

The radius of the nucleus was in the order of 3 × 10-14 m. (or very small compared to atom size)

P2.5.1 Atomic Structure

a) The basic structure of an atom is a small central nucleus composed of protons and neutrons surrounded by electrons. (Rutherford Model)

b) The relative masses and relative electric charges of protons, neutrons and electrons.

c) In an atom the number of electrons is equal to the number of protons in the nucleus. The atom has no overall electrical charge.

d) Atoms may lose or gain electrons to form charged particles called ions.

e) The atoms of an element always have the same number of protons, but have a different number of neutrons for each isotope. The total number of protons in an atom is called its atomic number. The total number of protons and neutrons in an atom is called its mass number.

Additional: Candidates should appreciate the relative size of the nucleus compared to the size of the atom.

P2.5.1 Atomic Structure

a) The basic structure of an atom is a small central nucleus composed of protons and neutrons surrounded by electrons. (Rutherford Model)

b) The relative masses and relative electric charges of protons, neutrons and electrons.

c) In an atom the number of electrons is equal to the number of protons in the nucleus. The atom has no overall electrical charge.

d) Atoms may lose or gain electrons to form charged particles called ions.

e) The atoms of an element always have the same number of protons, but have a different number of neutrons for each isotope. The total number of protons in an atom is called its atomic number. The total number of protons and neutrons in an atom is called its mass number.

Additional: Candidates should appreciate the relative size of the nucleus compared to the size of the atom.

P2.5.1 Atomic Structure

a) The basic structure of an atom is a small central nucleus composed of protons and neutrons surrounded by electrons. (Rutherford Model)

b) The relative masses and relative electric charges of protons, neutrons and electrons.

c) In an atom the number of electrons is equal to the number of protons in the nucleus. The atom has no overall electrical charge.

d) Atoms may lose or gain electrons to form charged particles called ions.

e) The atoms of an element always have the same number of protons, but have a different number of neutrons for each isotope. The total number of protons in an atom is called its atomic number. The total number of protons and neutrons in an atom is called its mass number.

Additional: Candidates should appreciate the relative size of the nucleus compared to the size of the atom.