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Questions:

A.    Atomic radius versus atomic number

A number of physical and chemical properties are related to the sizes of the atoms, but atomic size is somewhat difficult to define. There is no precise outer boundary of an atom. The radius is one half the distance between the centers of two adjacent atoms. The radius of an atom depends on the environment in whicd3h it is found. For bonded atoms, we customarily speak of a covalent radius, ionic radius, and, in the case of metals, a metallic radius. For atoms that are not bonded together, the radius is known as the van der Waals radius. For comparison, all radii in the above table are covalent.

1. Which is the largest of the first 54 elements?

Number 37’s (Rb) radius is the largest of the first 54 elements.

2. Describe how the atomic radius varies within a period and within a

Atomic radius decreases as one moves from left to right across a period. And atomic radius increases from up to down within a family.

3. Use your graph to predict the atomic radius of the following elements:

（a）Cesium  300pm      (b)    tungsten  210pm           (c)thallium   220 pm  (d)   radon  200 pm

4. Which group of the main group elements contains the largest elements?

The Group-1 has the largest atomic radius. It reduces over a period.

 

B.    Ionization energy versus atomic number

1. How would you explain ionization energy to your partner?

The atom loses electrons and becomes the energy required by ions.

• How does the ionization energy vary within a period and within a family?

lonization energy generally increases moving from left to right across an element period (row). And Ionization decreases moving top to bottom down an element group

• Which element on your graph has the strongest hold of its valence electrons?

He has the strongest hold of its valence electrons.

 

2. (a) Write the electron configuration for

Cl’s electron configuration will be 1s22s22p63s23p5.

(b)   Which electron is lost when 1251 kJ/mol of energy are applied to a sample of chlorine atoms?

3p

3. Compare the ionization energies of metals to

The Nonmetals have greater ionization energy, since they are on the right side of the periodic table and ionization energy – from left to right. Metal elements tend to lose electrons, so the ionization energy is smaller, and the non-metal is not easy to lose electrons, so the ionization energy is larger。

 

C.    Melting point versus atomic number

1. Describe the trend of melting points within a period

Melting points generally increase going from sodium to silicon, then decrease going to argon (with a “bump” at     sulphur).

2. Which group of elements tends to have the highest melting

Group 14.

3. Tungsten is used in incandescent light bulbs because it has an extremely high melting point. Which element on your chart could be a reasonable replacement for tungsten? Why?

It can be Carbon. Because Carbon has the largest melting points 3500.

 

D.    Density versus atomic number

1. Describe how density varies within a

Density is going up when going down in the period.

2. Compare the densities of the elements in the second period with the elements in the third

Density is going down in the second part of the period when travelling from left to right. And then going up in the third part of the period.

3. Assume that the transition metals given in the table are representative of the other members of this group. How do the densities of the transition metals compare with those of the elements in the main group?

The transition metals density is bigger than those of the elements in the main group.

4.Explain why aluminum and magnesium are more suitable than iron for use in some airplane.

Although the density of Fe is bigger than Al and Mg, Aluminum is sought after because it is abundant, fairly easy to obtain and very light. It’s also strong, resists corrosion and conducts both heat and electricity well. Alloys of aluminum are the primary metals that are used to build airplanes. Aluminum is alloyed with other metals like copper, magnesium and zinc to make it even stronger. The iron in the alloy become more resistant to rust.

 

E.    Electronegativity versus atomic number

1. Describe how electronegativity varies within a

Electronegativity increases across the Period from left to right.

2. Describe how electronegativity varies within a

Electronegativity tends to decrease moving down a group.

References:

 Kimball, D., E. Kuzub and M. Sanader (1993), Chemistry Laboratory Manual 1, Student’s Edition, Don Mills: Addison-Wesley Publishers Limited

Petrucci, R.H. (1982), General Chemistry, Principles and Modern Applications, 3rd ed. New York: Macmillan Publishing Co., Inc. Whitman, R.L., E.E. Zinck and R.A. Nalepa (1988), Chemistry Today 1, 3rd ed. Scarborough: Prentice-Hall Canada Inc.

Whitman, R.L., E.E. Zinck and R.A. Nalepa (1982), Chemistry Today Laboratory Manual, 2nd ed. Scarborough: Prentice-Hall Canada Inc.