The properties of materials

Introduction:

The properties of materials are the way they respond to the environment. These properties maybe mechanical, electrical and magnetic. Other important properties can be thermal or optical. Even chemical stability which measures the response of these materials with the environment like for example corrosion resistance or oxidation.

Table: 

1.      Why do ionic compounds dissolve in water?

Ionic compounds usually dissolve in water because water is a polar molecule with a permanent dipole. This means that when an ionic substance is place in water, the water molecules pull the positive and negative ions apart from each other. When this happens the ionic bonds of the compounds break and as a result the particles wander within the water.

2.      Why do covalent compounds dissolve in acetone?

So that it leads you build some basic conceptions like electronegativity, polarity, solubility, hydrogen bonding etc. Both of them are covalent compounds...ionic compounds are soluble in ionic solvents and covalent compounds are in covalent solvents. 'Like dissolves like'...is a simple way to explain the phenomenon. Both methanol and acetone are polar. There’re difference in electronegativitybetween -O-H [in methanol; hydrogen is therefore partially positive] and O=C< [in acetone; oxygen is partially negative]. That means, hydrogen bonding is formed, since they're polar...and this is why methanol is soluble in acetone. And one thing I must tell...both of them are miscible in water

3.      Why do metals conduct electricity?

Metals are good conductors because they have unfilled space in the valence energy band. Also, metals are soft, has a low melting point and happens to be reactive that’s why they can easily conduct heat/electricity easily. The electrical and thermal conductivity of metals originate from the fact, that in the metallic bond the outer electrons of the metal atoms form a gas of nearly free electrons, moving as an electron gas in a background of positive charge formed by the ion cores. Good mathematical predictions for electrical conductivity, as well as the electrons' contribution to the heat capacity and heat conductivity of metals can be calculated from the free electron model, which does not take the detailed structure of the ion lattice into account.

4.      Why do covalent compounds not conduct electricity?

Conditions for conducting electricity are delocalized or free electrons that can move throughout the structure and carry charge. In covalent compounds, there are no free electrons (as electrons are shared; there are no ions), so covalent compounds do not conduct electricity.

5.      Why do ionic compounds have such high boiling point?

Because the ionic bond is stronger than the covalent bond so it takes more energy (heat) to make the ions come apart. In a covalent bond the atoms share the electrons and neither atom has to give up its electrons completely. In an ionic compound like salt NaCl, the sodium gives up one electron which goes to join with the chlorine atom. So you have positive sodium atoms and negative chlorine atoms.

6.      Why do metals have such high boiling point?

Metals have strong metallic bonds. A lot of heat is required to break these bonds and thus resulting in high boiling and melting points.

Note: They don’t have ionic bonds, the have metallic bonds. 

Bibliography:

Antoine.frostburg.edu

General Chemistry Online: FAQ: Simple compounds: What properties distinguish ionic compounds from covalent compounds?

In-text: (Antoine.frostburg.edu, 2013)

Bibliography: Antoine.frostburg.edu (2013). General Chemistry Online: FAQ: Simple compounds: What properties distinguish ionic compounds from covalent compounds?. [online] Retrieved from: http://antoine.frostburg.edu/chem/senese/101/compounds/faq/properties-ionic-vs-covalent.shtml [Accessed: 30 Nov 2013].

Bbc.co.uk

BBC - GCSE Bitesize: Ionic compounds

In-text: (Bbc.co.uk, 2013)

Bibliography: Bbc.co.uk (2013). BBC - GCSE Bitesize: Ionic compounds. [online] Retrieved from: http://www.bbc.co.uk/schools/gcsebitesize/science/add_aqa_pre_2011/atomic/differentsubrev1.shtml [Accessed: 30 Nov 2013].

Bbc.co.uk

BBC - GCSE Bitesize: Metallic bonding

In-text: (Bbc.co.uk, 2013)

Bibliography: Bbc.co.uk (2013). BBC - GCSE Bitesize: Metallic bonding. [online] Retrieved from: http://www.bbc.co.uk/schools/gcsebitesize/science/add_ocr_gateway/periodic_table/metalsrev2.shtml [Accessed: 30 Nov 2013].

Virginia.edu.

Chapter 1. Introduction

In-text: (Virginia.edu, 2013)

Bibliography: Virginia.edu. 2013. Chapter 1. Introduction. [online] Available at: http://www.virginia.edu/bohr/mse209/chapter1.htm [Accessed: 30 Nov 2013].

Delete citation

WebsiteSEDE PALMIRA

Virtual.unal.edu.co.

SEDE PALMIRA

In-text: (Virtual.unal.edu.co, 2013)

Bibliography: Virtual.unal.edu.co. 2013. SEDE PALMIRA. [online] Available at: http://www.virtual.unal.edu.co/cursos/sedes/palmira/5000155/lecciones/lec3/3_1.htm [Accessed: 30 Nov 2013].