After Periodic Table, we began on atomic structure. To help us in this topic, besides the usual notes, worksheet and assignment, we were also provided a powerpoint to help us digest all this infomation at home if we did not understand what the teacher was teaching in class. Here are some of the notes.
The number of protons in an atom is called the proton number. Proton number is also known as the Atomic Number.
Nucleon number is the number of protons and neutrons in the nucleus of an atom. Nucleon number is also called the Mass Number.
Nucleon (Mass) number = number of protons + number of neutrons
The centre of an atom is called the nucleus which contains the protons and neutrons.
The electrons in an atom are arranged in shells (orbits) at different distances from the nucleus.
Note: Shells are also called energy levels.
Each shell can hold a certain maximum number of electrons.
(a) 1st shell - 2 electrons
(b) 2nd shell - 8 electrons
(c) 3rd shell - 8 electrons
(1st 20 elements only)
Advanced: For elements after calcium in the 4th period, their third shell can hold up to 18 electrons.
An atom can be described as an electrically neutral entity made up of a positively charged nucleus at its centre with negatively charged electrons moving around the nucleus.
All atoms of the same element have the same number of protons while those of different elements contain different number of protons.
Isotopes are atoms of the same element with different numbers of neutrons.
Only valence electrons are involved in chemical reactions.
Following this topic on atomic structure, it would go further and touch on the formation on ions, as well as chemical bonding.
Tuesday, March 8, 2011
Periodic Table
AS the fist topic in Lower Secondary Science, 2011, we studied on the periodic table. It was not a totally new concept to us as we touched on it last year. However, we got to study it deeper this year, giving us a better grasp on the topic. Here are some of the areas we learnt. (taken from the teacher's notes)
In the periodic table, the elements are arranged in order of increasing proton (atomic) number, and are classified according to Groups and Periods.
Group - a vertical set of elements
Period - a horizontal row of elements
The groups in the Periodic Table are numbered from I to VII and then Group 0. Some of these groups have names:
Group number Group
I Alkali metals
II Alkaline earth metals
VII Halogens
0 Noble gases
Elements between Group II and III are known as transition metals or transition elements.
Elements in the same group have similar chemical properties and will undergo the same type of chemical reactions.
Each period is numbered, 1, 2, 3, etc.
Elements in the 1st period will only have their 1st shell fully/partially occupied with electrons.
Elements in the 2nd period will have their 1st shell fully occupied with electrons, and their 2nd shell fully/partially occupied with electrons.
Down each group, the number of valence electrons is the same for each element and is equal to the group number.
Example: Group I Elements
Element Electronic configuration
Li 2.1
Na 2.8.1
K 2.8.8.1
Group I elements are very reactive. This similarity in reactivity is due to their electronic structure: one valence electron (advanced).
Generally, elements with small number of electrons in the valence shell (e.g. Group I and II) are metals. Elements with large number of electrons in the valence shell (e.g. Group VII and 0) are non-metals.
The line that divides metals from non-metals runs run diagonally through the Periodic Table. Elements found beside this dividing line are known as metalloids. Metalloids have some properties of non-metals and metals.
Charges on the ions formed are related to the group number and number of valence electrons.
Elements on the left side of the Periodic Table lose their valence electrons to form cations with charges corresponding to their group number. Elements on the right side of the Periodic Table gain electrons to form anions. The charges on the anions corresponding to the number of electrons gained to fill their valence shells with eight electrons.
I found that with all this infomation, I was able to answer the questions regarding the periodic table better than last year. The organisation of the notes is also very helpful and it makes revising for tests easier and more effecient
In the periodic table, the elements are arranged in order of increasing proton (atomic) number, and are classified according to Groups and Periods.
Group - a vertical set of elements
Period - a horizontal row of elements
The groups in the Periodic Table are numbered from I to VII and then Group 0. Some of these groups have names:
Group number Group
I Alkali metals
II Alkaline earth metals
VII Halogens
0 Noble gases
Elements between Group II and III are known as transition metals or transition elements.
Elements in the same group have similar chemical properties and will undergo the same type of chemical reactions.
Each period is numbered, 1, 2, 3, etc.
Elements in the 1st period will only have their 1st shell fully/partially occupied with electrons.
Elements in the 2nd period will have their 1st shell fully occupied with electrons, and their 2nd shell fully/partially occupied with electrons.
Down each group, the number of valence electrons is the same for each element and is equal to the group number.
Example: Group I Elements
Element Electronic configuration
Li 2.1
Na 2.8.1
K 2.8.8.1
Group I elements are very reactive. This similarity in reactivity is due to their electronic structure: one valence electron (advanced).
Generally, elements with small number of electrons in the valence shell (e.g. Group I and II) are metals. Elements with large number of electrons in the valence shell (e.g. Group VII and 0) are non-metals.
The line that divides metals from non-metals runs run diagonally through the Periodic Table. Elements found beside this dividing line are known as metalloids. Metalloids have some properties of non-metals and metals.
Charges on the ions formed are related to the group number and number of valence electrons.
Elements on the left side of the Periodic Table lose their valence electrons to form cations with charges corresponding to their group number. Elements on the right side of the Periodic Table gain electrons to form anions. The charges on the anions corresponding to the number of electrons gained to fill their valence shells with eight electrons.
I found that with all this infomation, I was able to answer the questions regarding the periodic table better than last year. The organisation of the notes is also very helpful and it makes revising for tests easier and more effecient
Wednesday, March 2, 2011
Science---Reflection on what I have learnt this year
This year, I have learnt many new topics in Science. I felt that the pace at which we were learning was very fast. I was able to understand most of the chemical bonding, periodic table and atomic structure. However, I only managed to understand a little on chemical equations. I found it hard to grasp on that topic, partly because it was a very new topic to me and I did not have sufficient time to study for it. I should have revised more on that topic before taking the test and I think that would have helped me a lot. While revising for my Science test, I found that the teacher's notes was very helpful. It summarises all the points that were required to learnt. This is very beneficial to our learning as the notes are also very clear. If we have any grey areas in the topic or we need help understanding something, that is where the notes come in handy. Secondly, I felt that the work done in the Science laboratory was very interactive and engaging, making our learning more fun. The Science experiments are also different from those last year. These Science experiment require more skill and have interesting but they could have potentially dangerous outcomes. This gives us the opportunity to practice self-control when in the laboratory as well as responsibility. We are also required to follow the laboratory rules strictly because the laboratory has many dangerous things and breaking of the rules could put our safety as well as that of others at risk. However, I still find that there could be more explanations for the class as to why this or that happened. I hope that I would be able to understand and grasp all the topics successfully in the subsequent terms and keep up with the pace at which we are going. I also hope to do better during Science laboratory lessons and be able to follow the instructions to the best of my ability.
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