Term 3 Reflections

Biology

My favourite subject. Somehow, I find it easier to understand biography than chemistry or physics, as it is telling us about what we observe about ourselves, wildlife, and the environment. With my more in-depth understanding, I was finally able to score an A1, even though it was a borderline A1, I felt satisfied with it, as I have not scored an A1 for Science until now. With more understanding, I might be able to do well for Chemistry and Physics too.

Term 2 Reflections

Term 2: Physics

In Term 2, we learned physics. Physics to me was rather interesting, but I was extremely confused by refraction, and whether the drawings we had to do were supposed to be extremely precise or just a rough estimation. We learned about light and light properties, with the main focus on reflection and refraction.

Reflection was pretty easy for me, but refraction made me do extremely badly, as I did not understand the concept well. Here are 2 diagrams depicting reflection and refraction, respectively.

The refractive index is calculated by sin i/ sin r, i being the angle of incidence and r being the angle of refraction.
There are 2 types of reflections, diffused and specular reflection. Specular reflection refers to the reflection when light reflects off a smooth surface, and diffused reflection when light reflects off a rough surface. The examples are below as below, respectively.

In most questions, we are required to draw the diagram for specular reflection. Well, reflection was a breeze for me, but refraction was what I was really bad at.

Refraction is basically the bending of light (refer to above diagram). Refraction affects us in many ways that we might not previously have known, such as, it helps myopic people to see clearly. Yes, I am talking about glasses, something that many people nowadays use daily. As you can see below, it is a side view of our eyeballs.

You might have noticed it seems similar to a pinhole camera. That is why refraction is able to help us see better, as myopia causes images to fall in front of our retina instead of on it, causing the images to become blurred. That is why spectacles are sometimes thicker than others, as it all depends on how much needs to be refracted. The many different kinds of spectacle lenses also have different refractive indexes, and so some might be more expensive than others.

Term 2 Test

For this test, I did really badly. I spent too much time on drawing, and left out 2 whole pages which were roughly 10 to 15 marks in total. That cost me a lot of marks and I barely scraped a pass out of the exam. I am determined to study harder for physics as I know it is just the refraction concept I am not too sure about, which also affected some of my drawings.

Term 1 Reflections

What I learnt

A term in Chemistry

This term, we were taught chemistry. To me, Chemistry is just mixing chemicals together to create new ones. I have never bothered to think deeper than that. However, in this one term that Chemistry was taught, I have learned more about it than I have ever had in my life. I personally think it was very fruitful, and I really enjoy the practical lessons we spent in the laboratory, mixing chemicals together and observing chemical reactions.

So here are the things that I have learnt:
-  Basic Chemical Calculations
- Acids and Bases
- Salts
- Atomic Structure
- Chemical Bonding
- Elements, Compounds, and Mixtures

Chemical Calculations

In Chemical Calculations, we basically were taught how to write chemical equations. One important point is that the equation has to be balanced. Here is an easy step-by-step guide on how to write a chemical equation for metaldehyde(C8H16O4), which burns in excess oxygen, producing carbon dioxide and water:
1. Write down the chemical formulas of the reactants and products of the reaction
     (C8H16O4--->CO2+H2O)
2. Balance the number of carbon and hydrogen atoms on both sides
    (C8H16O4--->8CO2+8H2O)
3. Balance the number of oxygen atoms
    (C8H16O4+10O2--->8CO2+8H2O)

And there you have it!

Acids and Bases

Some important definitions:
Acids- substances that produced H+ ions when dissolved in water
Strength of an acid- extent to which the acid molecule dissociates when dissolved in water
Base- reacts with an acid to form a salt and water only
Alkali- a base that is soluble in water
Neutralization reaction- Reaction between an acid and a base to form a salt and water only
Concentration- how much a substance is dissolved in 1 dm^3 of the solution
Strength- how easily an acid or an alkali dissociates when dissolved in water
pH scale- set of numbers used to show whether a solution is acidic, neutral or alkaline

In acids, the H+ ions are responsible for the properties of the acid, mainly:
- a sour taste
- conducts electricity in aqueous solution
- turns blue litmus paper red
- turns Universal Indicator orange or red
- reacts with reactive metals to form hydrogen and salt
  (metal + acid ---> salt + hydrogen)
This means that acids only show their properties when dissolved in water. Acids are also covalent compounds.
Acids have also many uses, such as:
Sulfuric acid- manufacture of detergents and fertilisers
Hydrochloric acid- leather processing and cleaning metals
Ethanoic acid- Used as flavouring agent for sour taste and as a food preservative

Properties of alkalis
- bitter taste
- soapy feel
- turns red litmus paper blue
- turns Universal Indicator green or violet
- reacts with acids to form salt and water only
- produces OH- ions when dissolved in water
- gives off ammonia gas when heated with ammonium salts

Some uses of bases and alkalis:
- Ammonia solution is used in cleaning solutions and fertilisers
- Calcium oxide is used in neutralizing acidic soil
- Sodium hydroxide is used in making soaps and detergents

pH scale ranges from 0 to 14, with pH <7 being acidic and >7 being alkaline. pH =7 is neutral.

Oxides

There are 4 types of oxides:
- Acidic oxide
- Basic oxide
- Amphoteric oxide
- Neutral Oxide

Here is an easy flow chart that can help you understand oxides better:

Term Test

I did very badly for the term test. I failed it, by a narrow margin. However, a fail will be a fail, and it was expected, as I could not really understand parts of it. Now, I understand the topics taught better, and the above 2 are the 2 subtopics that I think I am weaker in, compared to the others. I was extremely disappointed, as many science-related jobs require a good foundation in chemistry.

Welcome!

Welcome to my Science e-portfolio, that I will write my opinions and reflections of scientific happenings that are recent as well as what is taught in school. Although I am weak in Physics and Chemistry, I like Biology a lot, and hope that I can be a doctor in the future. I know it is a long road from here, so this is where I start.

-Ryan Ong