In term 2, we carried on with chemistry. There are 2 things that we learn about chemistry in term 2. They are equation writing and acid and bases which are all self-learning. In order to understand them well, I have to master my term 1 chemistry as what learnt in term 1 must be applied here.
To understand equation writing, first we would need to know what are ions. Ions are elements that are already stable, where their electrons filled the the entire shells they have. There are 4 types of ions. They are positive ions (cations), negative ions (anions), simple ions and polyatomic ions.
Aren't these chemical names familiar, that's right! All these elements are learnt in term 1 and now, we are just knowing the individual charges. After classifying them into cations and anions, we can move on to simple and polyatomic ions. Simple ions are formed from single atoms of such as magnesium atom and fluorine atom. Some elements form more than one type of positively charged ion, thus, when naming such ion, Roman numerals are used to indicate the number of charges, and are placed after the name of the metal.1 example will be magnesium oxide. Polyatomic ions, such as ammonium ion (NH4+), will consist of more than one type of atom. For example, the ammonium ion consists of one nitrogen atom and four hydrogen atoms chemically combined together. The ammonium ion has a charge of 1+ because the total number of protons in all of the atoms is one more than the total number of electrons. This charge of 1+ is not localized on any particular atom but spread over all the atoms in the ammonium ion.
Clearer with the ions formed by each elements? Now we can move on to chemical symbols. Chemical symbols includes balancing the polyatomic or simple ions. One example will be magnesium fluoride. Magnesium fluoride consists of Mg2+ and F- ions. Each Mg2+ ion must have 2 F- ions so that the negative and positive charges are balanced. Therefore, the formula of magnesium fluoride is MgF2. *Note: When there are more than one atoms of the same element, a subscript is used to represent the number of atoms of the element involved in bonding.
To be able to construct chemical equations, you must be very familiar with the cations and anions so that you know the charges to be dealt with. Therefore, just practice! Just try to form chemicals that are available with the elements and try to get used to the charges. With adequate practice, equation writing would be a breeze to you!
To move on, balancing the chemical equation is very important in equation writing. A balanced equation has the same number of atoms of each element on both sides of the equation.
It is totally different from just writing the equation in words.I shall use water as an example here.
Reaction between Oxygen and Hydrogen Water is formed when hydrogen gas is burnt in oxygen gas.
Chemical equation: 2H2 + O2 → 2H2 (simplest whole number ratio)
*Note: Always use a arrow to indicate and not an "=" sign
Well, this is the end of my lesson of equation writing. I took as long time to get used to equation writing as I practiced very long to be able to write chemical equations accurately. But I think I feel forget about this in the next semester, thus, I will refer to this again and refresh my memory! Now I move on talking about acid and bases.
My science teacher, Ms Nada, gave us a really good power-point slides about acid and bases. Since all of us have a basic knowledge on acid and bases in term 1, we could understand the information in the slides. In the slides, it summaries everything we did in term 1 and an introduction to neutralization.
In the slides, we were taught how to write the key points for acid and bases, examples of strong and weak acid, difference between strength and concentration of an acid, importance of water for acid, a recap in what we learn in term 1, how it reacts with a base (alkali), uses of such reaction and neutralization. All these stuffs are important things to take note of for my term 2 test, I am not going to miss out anything! :D
To understand equation writing, first we would need to know what are ions. Ions are elements that are already stable, where their electrons filled the the entire shells they have. There are 4 types of ions. They are positive ions (cations), negative ions (anions), simple ions and polyatomic ions.
Examples of cations and anions:
lithium
sodium
potassium
ammonium
copper (I)
Li+
Na+
K+
NH4+
Cu+
chloride
bromide
iodide
hydroxide
nitrate
Cl-
Br-
I-
OH-
NO3-
magnesium
calcium
iron (II)
copper (II)
Mg2+
Ca2+
Fe2+
Cu2+
carbonate
sulfide
sulfate
CO32-
S2-
SO42-
iron (III)
Fe3+
Aren't these chemical names familiar, that's right! All these elements are learnt in term 1 and now, we are just knowing the individual charges. After classifying them into cations and anions, we can move on to simple and polyatomic ions. Simple ions are formed from single atoms of such as magnesium atom and fluorine atom. Some elements form more than one type of positively charged ion, thus, when naming such ion, Roman numerals are used to indicate the number of charges, and are placed after the name of the metal.1 example will be magnesium oxide. Polyatomic ions, such as ammonium ion (NH4+), will consist of more than one type of atom. For example, the ammonium ion consists of one nitrogen atom and four hydrogen atoms chemically combined together. The ammonium ion has a charge of 1+ because the total number of protons in all of the atoms is one more than the total number of electrons. This charge of 1+ is not localized on any particular atom but spread over all the atoms in the ammonium ion.
Clearer with the ions formed by each elements? Now we can move on to chemical symbols. Chemical symbols includes balancing the polyatomic or simple ions. One example will be magnesium fluoride. Magnesium fluoride consists of Mg2+ and F- ions. Each Mg2+ ion must have 2 F- ions so that the negative and positive charges are balanced. Therefore, the formula of magnesium fluoride is MgF2.
*Note: When there are more than one atoms of the same element, a subscript is used to represent the number of atoms of the element involved in bonding.
To be able to construct chemical equations, you must be very familiar with the cations and anions so that you know the charges to be dealt with. Therefore, just practice! Just try to form chemicals that are available with the elements and try to get used to the charges. With adequate practice, equation writing would be a breeze to you!
To move on, balancing the chemical equation is very important in equation writing. A balanced equation has the same number of atoms of each element on both sides of the equation.
It is totally different from just writing the equation in words.I shall use water as an example here.
Reaction between Oxygen and Hydrogen
Water is formed when hydrogen gas is burnt in oxygen gas.
Word equation: hydrogen + oxygen → water
Writing in formula: H2 + H2 + H2 + H2 + O2 + O2 → H2O + H2O + H2O + H2O
4H2 + 2O2 → 4H2O
Chemical equation: 2H2 + O2 → 2H2 (simplest whole number ratio)
*Note: Always use a arrow to indicate and not an "=" sign
Well, this is the end of my lesson of equation writing. I took as long time to get used to equation writing as I practiced very long to be able to write chemical equations accurately. But I think I feel forget about this in the next semester, thus, I will refer to this again and refresh my memory! Now I move on talking about acid and bases.
My science teacher, Ms Nada, gave us a really good power-point slides about acid and bases. Since all of us have a basic knowledge on acid and bases in term 1, we could understand the information in the slides. In the slides, it summaries everything we did in term 1 and an introduction to neutralization.
In the slides, we were taught how to write the key points for acid and bases, examples of strong and weak acid, difference between strength and concentration of an acid, importance of water for acid, a recap in what we learn in term 1, how it reacts with a base (alkali), uses of such reaction and neutralization. All these stuffs are important things to take note of for my term 2 test, I am not going to miss out anything! :D