Science Infoblog

Here are the answers for the first seven worksheets in your organic chemistry booklet. Short test with selected questions on friday.

Worksheet 1

Worksheet 2

Worksheet 3

Worksheet 4

Worksheet 5

Worksheet 6

Worksheet 7

What happens when sodium and chlorine atoms react?

Sodium has one electron in its outer shell. Chlorine has seven electrons in its outer shell. When they react sodium loses an electron to become a sodium ion with a charge of +1. Chlorine atoms accept an electron to become chloride ions with a charge of -1. After reacting the sodium and chloride ions have a full outer shell of electrons. A full outer shell of electrons is a stable arrangement. The inert gasses in group 18 of the periodic table all have a full outer shell and characteristically are very unreactive (they don’t easily combine with other elements). The new substance sodium chloride is made up of ions. Compounds that have ions bonded together are called ionic. The ions are held together by powerful electrostatic forces. Ionic compounds typically have high melting and boiling points as a consequence.

Homework… how much of this do you understand?

Watch the video especially the bit that deals with the changes to sodium and chlorine atoms when they react with each other. Magnesium has two electrons in its outer shell and it burns in chlorine gas like sodium.
Draw sodium and chlorine atoms and show how ions are produced when they react.
What are the charges of the ions?
what is the formula of magnesium chloride?

How to prepare for the end of unit test

The end of unit test in Genetics will be on Thursday for 10SW and on Friday for 10 LE. Work through the tutorials at your own pace stopping the video to answer questions before moving on to view the correct answers. We will be going over material in class in the single lesson before the test. Make sure that you ask about any difficulties you experience during your study. You will need to prepare thoroughly to achieve the best result. This topic contains a lot of material.

Questions in NCEA level 3 chemistry papers

NCEA achievement standards contain clear statememnts of what you are expected to have mastered. Questions in the paper directly target each objective. There are a finite number of ways in which these objectives can be tested. If you go over recent papers thoroughly, ensuring that you fully understand each question taking note of the assessment schedules you will do well in the external exams.

Tackling the 2010 paper using a walkthrough.

• Make sure you have attempted questions 3 and 4 to the best of your ability.
• Study the walkthrough of questions three and 4 carefully then check that you can write complete answers by redoing the questions without assistance.

Walkthrough for As 90780 Particles and Thermochemistry 2010

Now attempt questions 1 and 2 from the same paper

The End of unit test for this achievement standard is next wednesday. Here is a practice paper for you to try and find out those aspects you need help with. Complete the paper as homework for Monday. I’ll put a tutorial answer on the blog on Monday for you to check your answers.

There will be a tutorial in Lab 52 tomorrow morning beginning at 7.30 when we will do this paper and you can sort out any issues then. I realise it is an early start but you will get your homework done and not need to slave over science during the weekend. It also signals to me that you are committed to getting a result in this externally assessed achievement standard. Good luck