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INTERNATIONAL ''BURCH'' UNIVERSITY SARAJEVO

Genetics and Bioengineering department

Lab

report

TOMIC STRUCTURE

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Student: Zlatan Husukic

Professor: Sevde Sevinghan

OBJECTIVES OF THIS EXPERIMENT ARE:

- Write the correct symbols or names of some elements

- Describe some physical properties of the elements

- Categoregorize an element as a metal or nonmetal from its physical

properties or location on the periodic table

-Write the complete symbol of an isotope including its mass numberand atomic number

- Use the complete symbol of an isotope to determine mass number,

atomic number, and number of protons, neutrons, and electrons

INTRODUCTION :

A chemical element is a purechemical substanceconsisting of one type

ofatomdistinguished by itsatomic number,which is the number of

protonsin itsnucleus.Elements are divided intometals,metalloids,andnon-metals.Familiar examples of elements includecarbon,oxygen

(nonmetals),silicon,arsenic(metalloids),aluminium,iron,copper,gold,

mercury,andlead (metals).

As of 2010, there are 118 known elements . 98 of them occur naturally

on Earth.

Lists of the elements are availableby name,by symbol,by atomic number,bydensity,by melting point,andby boiling pointas well asionization energies of

the elements.The nuclides of stable and radioactive elements are also available

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as alist of nuclides,sorted by length of half-life for those that are unstable. One

of the most convenient, and certainly the most traditional presentation of the

elements, is in form ofperiodic table,which groups elements with similar

chemical properties (and usually also similar electronic structures) together.

In the standard periodic table, the elements are listed in order of increasingatomic number (the number ofprotonsin thenucleusof an atom). A new row

(period)is started when a new electron shell has its first electron. Columns

(groups)are determined by theelectron configurationof the atom; elements withthe same number of electrons in a particular subshell fall into the same columns

(e.g.oxygenand

seleniumare in the same column because they both have four electrons in the

outermost p-subshell).

Elements with similar chemical properties generally fall into the same group in

the periodic table.

Metals are located on the right side of the periodic table, and nonmetals arelocated on the right side.

The groups are numbered acriss the top of the chart. Elements in Group 1 arealkali metals, elements in group 2 are the alkaline earths, and Group 7 contains

the halogens. Group 8 contains the noble gases. A dark zigzag line that looks

like a staircase seperates the metals on the left side from the nonmetals on the

right side.

Elements

Elements consist of only one kind of atom and cannot be decomposed intosimpler substances.

Our planet is made up of some 90 elements. (Tiny amounts sometimes only a

few atoms of additional elements have been made in nuclear physics

laboratories, but they play no role in our story). Of these 90, only 25 or soareused to build living things.

The table shows the 11 most prevalent elements in the lithosphere (the earth'scrust) and in the human body.

Elemental composition of the

lithosphere and the human body.

Each number represents the percent

of the total numberof atoms

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Living matter

uses only a fraction of the elements

available to it

but, as the table shows, the relativeproportions of those it does acquire

from its surroundings are quite

different from the proportions in theenvironment.

So,

the composition of living things is

not simply a reflection of theelements available to them

For example, hydrogen, carbon, and

nitrogen together represent less than

1% of the atoms found in the earth's

crust but some 74% of the atoms inliving matter.

one of the properties of life is to

take up certain elements that arescarce in the nonliving world andconcentrate them within living cells.

Some sea animals accumulate

elements like vanadium and iodine

within their cells to concentrations a

thousand or more times as great as

in the surrounding sea water. It haseven been proposed that uranium be

"mined" from the sea by extracting

it from certain algae that can take

up uranium from sea water andconcentrate it within their cells.

There is still some uncertainty about the exact number of elements required by

living things. Some elements, e.g., selenium and aluminum, are found in tiny

amounts within living things, but whether they are playing an essential role

(selenium is)or are simply an accidental acquisition (aluminum probably) is

sometimes difficult to determine.

present. For example, 47 of every

100 atoms found in a representative

sample of the lithosphere are oxygen

while there are only 19 atoms of

carbon in every 10,000 atoms of

lithosphere.

Composition of

the Lithosphere

Composition of

the Human Body

Oxygen 47 Hydrogen 63

Silicon 28 Oxygen 25.5

Aluminum 7.9 Carbon 9.5

Iron 4.5 Nitrogen 1.4

Calcium 3.5 Calcium 0.31

Sodium 2.5 Phosphorus 0.22

Potassium 2.5 Chlorine 0.03

Magnesium 2.2 Potassium 0.06

Titanium 0.46 Sulfur 0.05

Hydrogen 0.22 Sodium 0.03

Carbon 0.19 Magnesium 0.01

All others

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Atoms

Each element is made up of one kind of atom. We can define an atom as the

smallest part of an element that can enter into combination with other elements.

Structure of the atom

Each atom consists of

a small, dense, positively-chargednucleus surrounded by much lighter, negatively-charged electrons.

The nucleus of the simplest atom, the hydrogen atom(H), consists of

a single positively-charged proton. Because of its single proton, theatom of hydrogen is assigned an atomic numberof 1.

a single electron.

The charge of the electron is the same magnitude as that of the proton, so the

atom as a whole is electrically neutral. Its proton accounts for almost all the

weight of the atom.

The nucleus of the atom of the element helium(He) has

two protons(hence helium has an atomic numberof 2) and

two neutrons. Neutrons have the same weight as protons but no electricalcharge.

The helium atom has two electronsso that, once again, the atom as a whole is

neutral.

The structure of each of the other kinds of atoms follows the same plan. From

Lithium (At. No. = 3) to uranium (At. No. = 92), the atoms of each element can

be listed in order of increasing atomic number. There are no gaps in the list.Each element has a unique atomic number and its atoms have one more protonand one more electron than the atoms of the element that precedes it in the list.

Electrons

Atomic Number Element

Energy Levels or "shells"

K L M N O

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1 Hydrogen(H) 1

2 Helium (He) 2

3 Lithium (Li) 2 1

4 Beryllium (Be) 2 2

5 Boron (B) 2 3

6 Carbon(C) 2 4

7 Nitrogen(N) 2 5

8 Oxygen(O) 2 6

9 Fluorine(F) 2 7

10 Neon (Ne) 2 8

11 Sodium(Na) 2 8 1

12 Magnesium(Mg) 2 8 2

13 Aluminum (Al) 2 8 3

14 Silicon(Si) 2 8 4

15 Phosphorus(P) 2 8 5

16 Sulfur(S) 2 8 6

17 Chlorine(Cl) 2 8 7

18 Argon (Ar) 2 8 8

19 Potassium(K) 2 8 8 1

20 Calcium(Ca) 2 8 8 2

21 Scandium (Sc) 2 8 9 2

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Electrons are

confined to

relatively

discrete

regionsaround thenucleus. The

two electrons

of helium, for

example, are

confined to aspherical

zone

surrounding

the nucleus

called the Kshellor Kenergy level.

Lithium (At.No. = 3) has

three

electrons, two

in the K shelland one

locatedfarther from

the nucleus in

the L shell.

Being farther

away fromthe opposite

(+) charges ofthe nucleus,

this third

electron is

held lesstightly.

Each of the

following elements, in order of increasing atomic number, adds one more

electron to the L shell until we reach neon (At. No. = 10) which has eightelectrons in the L shell.

22 Titanium (Ti) 2 8 10 2

23 Vanadium(V) 2 8 11 2

24 Chromium(Cr) 2 8 13 1

25 Manganese(Mn) 2 8 13 2

26 Iron(Fe) 2 8 14 2

27 Cobalt(Co) 2 8 15 2

28 Nickel(Ni) 2 8 16 2

29 Copper(Cu) 2 8 18 1

30 Zinc(Zn) 2 8 18 2

31 Gallium (Ga) 2 8 18 3

32 Germanium (Ge) 2 8 18 4

33 Arsenic(As) 2 8 18 5

34 Selenium(Se) 2 8 18 6

35 Bromine (Br) 2 8 18 7

36 Krypton (Kr) 2 8 18 8

42 Molybdenum(Mo) 2 8 18 13 1

48 Cadmium(Cd) 2 8 18 18 2

50 Tin(Sn) 2 8 18 18 4

53 Iodine(I) 2 8 18 18 7

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Sodiumplaces its eleventh electron in a still higher energy level, the M shell.

From sodium to argon, this shell is gradually filled with electrons until, onceagain, a maximum of eight is reached.

Note that after the K shell with its maximum of two electrons, the maximumnumber of electrons in any other outermostshell is eight.

As we shall see, the chemical propertiesof each element are stronglyinfluenced by the number of electrons in its outermost energy level(shell).

This table shows the electronic structure of the atoms of elements 1 36 with

those that have been demonstrated to be used by living things shown in red.

Four elements of still higher atomic numbers that have been shown to be used

by living things are also included.

The electronic structure of an atom plays the major role in its chemistry.

The pattern of electrons in an atom especially those in the outermost shell

determines

the valenceof the atom; that is, the ratios with which it interacts with

other atoms, and to a large degree,

the electronegativityof the atom; that is, the strength with which itattracts other electrons.

Elements with the same number of electrons in their outermost shell show

similar chemical properties.

Example 1: Fluorine, chlorine, bromine, and iodineeach have 7 electrons in

their outermost shell. These so-called halogensare also quite similar in their

chemical behavior. When dissolved in water, for example, they all producegermicidal solutions.

Example 2: Those elements with 1, 2, or 3 electrons in their outermost shell arethe metals.

Example 3: Those elements with 4, 5, 6, or 7 in their outermost shell are the

nonmetals.

Example 4: Helium(with its 2), neon, argon, and krypton(each with 8) have

"filled" their outermost shells. They are the so-called inert or "noble" gases.

They have no chemistry at all. Under normal conditions they do not interact with

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other atoms. So, it is the number and arrangement of the electrons in the atoms

of an element that establish the chemical behavior of that element.

This is how it works.

The atoms of an element interact with other atoms in such ways and ratios that

they can "fill" their outermost shell with 8 electrons(2 for hydrogen). They may

do this by

acquiring more electrons from another atom

losing electrons to another atom sharing electrons with another atom

The number of electrons that an atom must acquire, or lose, or share to reach astable configuration of 8 (2 for hydrogen) is called its valence.

Hydrogen, lithium, sodium, and potassium atoms all have a single electron in

their outermost shell. Fluorine, chlorine, bromine, and iodine atoms all have 7.

Any atom of the first group will interact with a single atom of any of the secondgroup forming, HCl, NaCl, KI, etc. The result of all of these interactions is a pair

of atoms each with an outermost shell like that of one of the inert gases: 2 for

hydrogen, 8 for the others.

The elements with 2 electrons in their outermost shell interact with chlorine andthe other halogens to form, e.g., BeCl2, MgCl2, CaCl2. Again, the result is a pairof atoms each with a stable octet of electrons in its outermost shell.

The elements with 3 electrons in their outermost shell will interact with chlorinein a ratio of 1:3, forming BCl3, AlCl3.

Carbonatoms, with their 4 electrons in the L shell interact with chlorine toform CCl4.

Nitrogen, with its 5 outermost electrons, interacts with hydrogen atoms in aratio of 1:3, forming ammonia (NH3).

Oxygenand sulfur, with their 6 outermost electrons react with hydrogen to

form water (H2O) and hydrogen sulfide (H2S).

What determines whether a pair of atoms swap or share electrons?

The answer is their relative electronegativities. If two atoms differ greatly in

their affinity for electrons; that is, in their electronegativity, then the strongly

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electronegative atom will take the electron away from the weakly

electronegative one.

Example: Na (weakly electronegative) gives up its single electron to an atom of

chlorine (strongly electronegative) to form NaCl. The sodium atom now hasonly 10 electrons but still 11 protons so there is a net positive charge of one on

the atom. Similarly, chlorine now has one more electron than proton so its now

has a net negative charge of 1. Electrically charged atoms are called ions. The

mutual attraction of opposite electrical charges holds the ions together by ionicbonds.

Example: Carbon and hydrogen are both only weakly electronegative so neithercan remove electrons from the other. Instead they achieve a stable configuration

by sharing their outermost electrons forming covalent bondsof CH4.

Isotopes

The number of protons in the nucleus of its atoms, which is its atomic number,

defines each element. However, the nuclei of a given element may have varyingnumbers of neutrons. Because neutrons have weight (about the same as that of

protons), such atoms differ in the atomic weight.

Atoms of the same element that differ in their atomic weight are called isotopes.

Atomic weights are expressed in terms of a standard atom: the isotope of carbon

that has 6 protons and 6 neutrons in its nucleus. This atom is designated carbon-

12or12

C. It is arbitrarily assigned an atomic weight of 12 daltons(named after

John Dalton, the pioneer in the study of atomic weights). Thus a dalton is 1/12

the weight of an atom of12

C. Both protons and neutrons have weights very close

to 1 dalton each. Carbon-12 is the most common isotope of carbon. Carbon-13

(13

C) with 6 protons and 7 neutrons, and carbon-14 (14

C) with 6 protons and 8neutrons are found in much smaller quantities.

Isotopes as "tracers"

One can prepare, for example, a carbon compound used by living things that has

many of its normal12

C atoms replaced by14

C atoms. Carbon-14 happens to be

radioactive. By tracing the fate of radioactivity within the organism, one canlearn the normal pathway of this carbon compound in that organism. Thus 14C

serves as an isotopic "label" or "tracer".

The basis of this technique is that the weight of the nucleus of an atom has little

or no effect on the chemical properties of that atom. The chemistry of anelement and the atoms of which it is made whatever their atomic weight is

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a function of the atomic numberof that element. As long as the atom had 6

protons, it is an atom of carbon irrespective of the number of neutrons. Thus

while 6 protons and 8 neutrons produce an isotope of carbon,14

C, 7 protons and7 neutrons produce a totally-different element, nitrogen-14.

Isotonesare atoms (nuclides)of differentchemical elementsthat have the very

sameneutron numberN, but differentproton numberZ and mass numbar A.

For example, boron-12 and carbon-13 nuclei both contain 7neutrons,and so are

isotones

Isobarsare atoms (nuclides)of differentchemical elementsthat have the same

number ofnucleons.Correspondingly, isobars differ inatomic number(or

number ofprotons)but have the samemass number.

An example of a series of isobars would be40S,40Cl,40Ar,40K,and40Ca.The

nuclei of these nuclides all contain 40 nucleons, however they contain varying

numbers of protons and neutrons.

Two or moremolecular entities(atoms,molecules,orions)are described as

being isoelectronicwith each other if they have the same number of electrons or

a similarelectron configuration.

TheNatom and theO+radicalion are isoelectronic because each has five

electrons in the outer electronic shell.

Physical Properties of M etals:

- Luster (shininess)

- Good conductors of heat and electricity

- High density (heavy for their size)

- High melting point

- Ductile (most metals can be drawn out into thin wires)

-Malleable (most metals can be hammered into thin sheets)

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Chemical Properties of M etals:

- Easily lose electrons

- Corrode easily (silver tarnishing and iron rusting)

Physical Properties of Nonmetals:

- No luster (dull appearance)

- Poor conductor of heat and electricity

- Brittle (breaks easily)

-Not ductile

- Not malleable

- Low density

- Low melting point

Chemical Properties of Nonmetals:

- Tend to gain electrons

Physical Properties of Metalloids:

- Solids

- Can be shiny or dull

- Ductile

- Malleable

-

Conduct heat and electricity better than nonmetals but not aswell as metals

Atoms are the basic building units of matter around us. Atom is consists of threebasic particles: positively charged protons, negatively charged electrons and

neutral neurons. Each atom is a different combination of these particles. The

combination of these particles decides the properties of matter. Electrons

revolve around the nucleus. The nucleus is at the center of the atom and consistsof protons and neutrons. The pathway of electrons around the nucleus is called

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orbit. An atom is neutral due to equal number of electrons in the orbits and

number of protons in the nucleus.

An atom or molecule in which the total number of electrons is not equal to thetotal number of protons is called an Ion. It carries either negative or positive

charge.

Ions can be created by both chemical and physical means. In chemical terms, if a

neutral atom loses one or more electrons, it has a net positive charge and is

known as acation.If an atom gains electrons, it has a net negative charge and is

known as ananion.An ion consisting of a single atom is an atomic

ormonatomic ion;if it consists of two or more atoms, it is amolecularorpolyatomic ion.

Theatomic numberof an element is equal to the number of protons that definesthe element. For example, all carbon atoms contain 6 protons in theirnucleus;so

the atomic number of carbon is 6.

The symbol for atomic number is Z. This conventional symbol Z possibly comesfrom theGermanword Atomzahl (atomic number).However, prior to 1915, the

word Zahl (simply number) was used for an element's assigned number in the

periodic table.

Themass numberof an element, A, is the number ofnucleons

(protons and neutrons) in the atomic nucleus.The mass number is always a

simple whole number and has units of "nucleons." An example of use of a massnumber is "magnesium-24," which has 24 nucleons (12 protons and 12

neutrons).The mass number is written either after the element name or as a superscript to

the left of an element's symbol. For example, the most common isotope

ofcarboniscarbon-12,or 12C, which has 6 protons and 6 neutrons.

The difference between the mass number and the atomic number gives

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thenumber of neutrons(N) in a given nucleus: N=AZ.

Report SheetA. Physical Properties of Elements

Element Symbol Atomic

number

Physical Properties

Color Luster

Metal/

Nonmetal

Aluminium Al 13 Silver/grey Shiny Metal

Carbon C 6 Black/grey Dull Nonmetal

Copper Cu 29 Reddish

brown

Shiny Metal

Iron Fe 26 Silver Shiny Metal

Magnesium Mg 12 Grey/white Shiny Metal

Nickel Ni 28 Silver Shiny Metal

Nitrogen N 7 Colorless Dull Nonmetal

Oxygen O 8 Colorless Dull Nonmetal

Phosphorus P 15 Red or white Dull Nonmetal

Silicon Si 14 Grey/blue Shiny Metalloid

Silver Ag 47 Silver Shiny Metal

Sulfur S 16 Yellow Dull Nonmetal

Tin Sn 50 Silver-white Dull

(pure is

shiny)

Metal

Zinc Zn 30 Blue/gray Shiny Metal

REFERENCE :

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www.wikkipedia.com

www.chemistry-online.com

papres that professor gave us on lesson