chemistry - periodic functions

Question 1

define periodic law?

Answer 1

properties of an element are periodic functions of they atomic number is know as periodic law

Question 2

periodic function?

Answer 2

1) metallic properties of elements
2) electronegativity
3) first ionisation energy
4) valency

Question 3

5 main Metallic properties of elements ?

Answer 3

1) metals - Li, Be ,Na ,Mg ,Al ,P ,Ca
2) solid non metals - C ,S,P
3) reactive gasses - H ,N ,O ,F ,Cl
4) noble gasses - He ,Ne , Ar
5) metaloids - B, Si

Question 4

what are the physical properties of metals

Answer 4

have a metallic luster
sonorous
malleable
exist in a solid-state at room temperature

Question 5

what are the chemical properties of metals?

Answer 5

1) by combining with oxygen basic oxides are formed
2) when oxides are dissolved in water basic solutions are formed
3) metals for positive ions or cations when an electron is removed

Question 6

Physical properties of sodium (Na)?

Answer 6

sodium is a soft metal
good heat and electricity conductor
sodium has a low density than water so it floats in water

Question 7

chemical properties of sodium

Answer 7

1) it has a very fast reaction between oxygen and water vapor
2) it reacts vigorously with water
3) it reacts fast with dilute acid and explodes

Question 8

uses of sodium?

Answer 8

produce sodium cyanide
produce sodium amalgam
produce indigo dye
use for extraction of metals from their compound

Question 9

physical properties of magnesium?

Answer 9

good conductor for heat and electricity

has a higher density than water

Question 10

chemical properties of magnesium

Answer 10

it burns in air with white flame
it does not react with cold water
it react fast with dilute acid

Question 11

uses of magnesium

Answer 11

1) use to produce medicine
2) use as a metal that prevents corrosion of iron
3) produce magnelium
magnesium + aluminum = magnelium ( is an alloy that is strong and resistant to corrosion it is used in the aircraft industry and to make parts for automobiles)

Question 12

3 types of solid non-metals?

Answer 12

reactive gasses
noble gasses
solid non metals

Question 13

physical properties if carbon

Answer 13

most of the carbon forms are in black colour (except diamond)
carbon has a low density ( except diamond )
poor conductor for electricity ( except graphite)

Question 14

chemical properties of cabon

Answer 14

carbon are very low reactive elements

Question 15

uses of carbon

Question 16

physical properties of sulphur

Answer 16

it’s a yellow color solid
it has a very unpleasant smell
it dissolve in water but highly dissolve in carbon disulphide

Question 17

chemical properties of sulphur

Answer 17

it burns in the air with a bright blue flame

it burns with different metals and forms metal sulphide

Question 18

2 types of non metallic gasses?

Answer 18

reactive gasses

noble gasses

Question 19

what are reactive gasses

Answer 19

gasses which naturally exists in atomic molecules

H ,N ,O , F, Cl

Question 20

physical properties of nitrogen

Answer 20

it’s colorless and odorless

it’s lighter than air and its slightly soluble in water

Question 21

chemical properties if nitrogen

Answer 21

its a very low reactive element
it’s nonsupport to combustion
it reacts with magnesium at a high temperature

under special conditions, it reacts with hydrogen and forms ammonia(a good fertilizer)

Question 22

uses if nitrogen

Answer 22

it’s used when packaging milk powder packet
nitrogen liquid is used as a coolant
its also used to fill vehicle tires
used to fill electric bulbs and thermometers

Question 23

what are noble gasses

Answer 23

helium He
neon Ne
argon Ar

Question 24

why noble gasses are refered as no reactive gasses

Answer 24

since they maximum number of electrons in there outer shell. they do not react to others

Question 25

what are metolloids?

Answer 25

elements that have metallic and non-metallic properties are known as metalloids.

Question 26

uses if silicon

Answer 26

use to make diodes and transistors use to make solar cells used to make computer equipments

Question 27

uses of boron

Answer 27

use as a welding metal use to make skin cream use to make glass tubes that can be heated at a high temperature

Question 28

what are allotropes

Answer 28

elements which have different forms are known as allotropes

Question 29

what are the two allotropes that carbon have

Answer 29

crystalline carbon - diamond, graphite, fluorine amorphous carbon - coal ,charcoal ,lamp , sout

Question 30

allotropes of oxygen

Answer 30

``` atmospheric oxygen ( O2 ) ozone (O3) ```

Question 31

allotropes of sulphur

Answer 31

Rhombus sulphur Crystalline sulphur amofores sulphur

Question 32

what is valency

Answer 32

all the element atoms needed to be stable in the outer shell. to stable the outer shell some atoms release or gain some electrons to stable their outer shell .these number of electrons is known as valency.

Question 33

there are 2 types of chemical formulae

Answer 33

1) simple chemical formulae | 2) complex chemical formulae

Question 34

how write simple chemical formulae

Answer 34

write the lowest group number of elements first change the valency and right keep the simplest form for that valency

Question 35

how to write complex chemical formulae

Answer 35

first, wright metal and then wright polyatomic group | keep the formulae in the simplest form

Question 36

what are Isotopes

Answer 36

the same element atom with different atomic masses are known as Isotopes

Question 37

what are isotopes of hygrogen

Answer 37

protium deuterium Titrium

Question 38

what is first ionization energy?

Answer 38

the first Ionization energy of an element is the minimum energy that should be supplied to an atom in the gaseous state to remove an electron and to form a unipositive gaseous ion.

Question 39

what is Electronegativity

Answer 39

Electronegativity means the ability of an atom of an element to attract an electron of a bond towards itself when its attached to another element the attraction of of higher electronegativity is greater than the lower electronegativity.

Question 40

the nature of oxides in elements in the 3rd period

Answer 40

``` Na - strongly basic Mg - weakly basic Al - amphoteric Si - very weakly acidic P - weakly acidic S - strongly acidic Cl - very strongly acidic ```