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KEBUMEN REGENCY GOVERMENT

EDUCAT ION AND CULTURE OFF ICE

STATE SENIOR HIGH SCHOOL KEBUMEN 17 Mayjen Sutoyo Street Kebumen Phone (0287) 381407 Zip Code 54316

E-ma il : sma_I_kbm @ yahoo.com

Home page : http://www.sma1-kebumen.sch.id

ANSWER OF CHEMISTRY ENRICHMENT

 N a m a : A l i f S a p u t r a

S u b j e c t : Chemistry

Class : X/5

Amount of Problem : E ss ay : 5 problems

Kind of Test : Written Test

Day, Date : Friday, 23 October 2009

Time Allocation : …………minutes

METALS, METALLOIDS, AND NONMETALS

1. What's the difference between a chemical and a physical property? Give two

examples of each and explain how  they are different.

Answer : A chemical change cannot be changed back to its original form e.g.wood burning in a fire place. where as a physical change can be

changed back to its original form e.g. water can be changed into ice

and ice can be changed back to water, its original form. Physical properties are those that can be observed without changing the

identity of the substance. The general properties of matter such as

color, density, hardness, are examples of physical properties.

Properties that describe how a substance changes into a completelydifferent substance are called chemical properties. Flammability and

corrosion/oxidation resistance are examples of chemical properties.

2. Give four properties that are generally present in metals.Answer : 1. Its atoms are very tightly,

2. Be forged,3. Solid at room temperature,

4. Conductor 

3. If steel (a metal) is hard and granite (a nonmetal) is hard, why don't we make

automobile engines out of granite?

Answer : Because granite is a non-metal that can not be forged to make the dials

chassis

4. What are metalloids used for, and how does this affect modern technology?

Answer : as pesticides (As), fiber optics and plastic surgery (Si), as an amplifier of 

lead & lighter materials (Sb),

nuclear testing (Po).

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PERIODIC TRENDS

1) Rank the following elements by increasing atomic radius: carbon,

aluminum, oxygen, potassium.

Answer : 1. Oxygen (O) : 48 pm

2. Carbon (C) : 67 pm

3. Aluminum (Al) : 118 pm

4. Pottasium (K) : 243 pm

2) Rank the following elements by increasing electronegativity: sulfur, oxygen,

neon, aluminum.

Answer : 1. Neon (Ne) : 0

2. Aluminum (Al) : 1,61

3. Sulfur (S) : 2,58

4. Oxygen : 3,44

3) What is the difference between electron affinity and ionization energy?

Answer :  

Electron Affinity Ionization Energy

Release Electron Absorb Electron

Absorb and release energy Absorb EnergyForming ionic with charged -1 Forming ionic with charged +1

4) Why does fluorine have higher ionization energy than iodine?

Answer : because iodine has a number of skin and electrons are more

 protective than fluorine (skin & ep of I: 5 & 46, while the skin & ep of F: 2 & 2), it

was the influence of gravity causes the core to the valence electrons are owned by

the fluorine becomes smaller, while the influence of gravity forces the core to the

valence electrons are owned by Iodine becomes larger than fluorine, so the value of 

the ionization energy of fluorine is greater than the iodine.

5) Why do elements in the same family generally have similar properties?

Answer :  because these elements have a number of the same valence electrons

1. A chemical property describes how something will react. It burns, it reacts with

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oxygen, it is gives away electrons, it takes electrons, it is inert

A chemical change is where a compound is formed or decomposed. elements

replace another or switch places with another in a compound.A chemical reaction isnoted if a precipitate is formed, a gas is given off, a color change takes place, or 

there is a great energy change.

A physical property describes how a piece of matter looks, color, shape, size,state,

etc sugar is a white crystal

A physical change is a change in size, shape state or solution.When sugar goes into

solution or out, it is a physical change.

2. They have metallic shine or luster.solids at room temperature.malleable. Malleable

means that metals can be hammered, pounded, or pressed into different shapes

without breaking. good conductors of heat and electricity

Properties of metal

The properties of metals vary.

Most metals are a gray color, but some like bismuth, copper,and gold are different.

Some metals even show more than one color(pleochroism).

The melting points of metals vary.

Density also varies.

The metal with the lowest electrical conductivity is Bismuth, and silver has the highest. Theconductivity of most metals will lower when alloyed.

All metals expand when heated and contract when cooled.

Metals are usually strong and resistant to stress, but each one is different. Metals are graded

 by

Hardness, (the resistance to surface deformation)

Tensile strength (resistance to breaking)

Elasticity (ability to take their original shape after deforming)

Malleability (ability to be shaped)

Fatigue resistance (resistance to repeated stress)

Ductility (ability to be deformed without breaking).

Metals mostly have positive valences, which means they donate electrons to the atoms theyare bonded to.

Metals tend to form basic oxides.

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3. : Because granite is a non-metal that can’t be forged to make the dials

chassis

4.