atoms and molecules class 9

 all the matter in the universe that we know of is made of tiny, invisible particles

called atoms. atoms are crammed into everything you can see - from the skin on your 

fingers to the words in this  book  things you can not see too, such as the air you breathe 

and the cells rushing through your blood.

THE IDEA OF ATOMS IS ONE OF THE OLDEST IN SCIENCE. SOME 

ANCIENT GREEK PHILOSOPHERES  THOUGH ATOMS WERE THE 

SMALLEST POSSIBLE  BITS OF MATTER AND COULD NOT BE

BROKEN DOWN FURTHER. THEY CHOSE THE NAME ATOM BECAUSE 

IT MEANS "UNCAUNTABLE"OR "INDIVISIBLE". THIS EARLY CONCEPT 

OF ATOMS LIVED ON FOR THOUSANDS OF YEARS, UNTIL, INTHE EARLY

20TH CENTURY , INGENIOUS SCIENTISTS "SPLITTHE ATOM", SAMASHING IT APART

INTO EVEN TINIER PARTICLES. WHEN ATOMS COMBINE , THEY MAKE BIGGER 

CLUMPS CALLED MOLECULES. ALTHOUGH THERE ARE ONLY ABOUT 100

TYPES OF ATOM, TOGETHER THEY CAN FORM MILLIONS OF DIFFERENT 

TYPES OF MOLECULES.

THE NUCLEUS 

 

A CLUSTER OF PROTONS AND NEUTRONS MAKE UP THE NUCLEUS OF AN 

ATOM. IT MAKE UP MOST OF AN ATOM'S WEIGHT , BUT ONLY TAKES UP TINY 

AMOUNT OF ITS VOLUME. OUTSIDE THE NICLEUS, MORE THAN 99.99 PER CENT 

OF AN ATOM IS JUST EMPTY SPACE. IF AN ATOM WERE THE SIZE OF FOOTBALL

STADIUM, THE NUCLEUS WOULD BE THE SIZE OF A PEA IN THE CENTRE OF IT, AND 

THE ELECTRONS WOULD BE ZOOMING AROUND THE OUTER STANDS.

NEUTRON

THESE ARE AROUND THE SAME SIE AS PROTONS. NEUTRONS ARE NEUTRAL, 

WHICH MEANS THEY DO NOT HAVE ELECTRIC CHARGE AND AREN'T ATTRACTED

TO ELECTRON OR PROTONS.

ELECTRON SHELLS

 

AN ATOM USALLY HAS AN EQUAL NUMBER OF NEGETIVILY CHARGED

ELECTRON AND POSITIVILY CHARGED PROTONS. SOME BIG ATOMS HAVE

MORE THAN 100 OF BOTH. THE CARBON ATOM SHOWN HERE HAS SIX OF EACH.

ELECTRONS ARE ARRANGED IN LAYERS (CALLED ELECTRON SHELLS) AROUND 

THE NUCLEUS, LIKE SATELLITES AROUND A PLANET. BIGGER ATOMS HAVE 

MORE SHELLS THAN SMALLER ONES. IMAGINING ELECTRONS IN SHELLS 

IN SHELLS HAVE HELPS UP TO UNDERSTAND HOW ATOMS OIN TOGETHER 

TO FORM MOLECULES. 

ELECTRON

THESE PARTICLES ARE ABOUT 2,000 TIMES LIGHTER ARE

PROTONS AND NEUTRONS AND ORBIT THE NUCLEUS AT ALMOST

THE SPEED OF LIGHT. THEY HAVE A NEGATIVE ELECTRIC CHARGE.

 THE STRUCTURE OF AN ATOM 

INSIDE AN ATOM ARE EVEN TINIER PARTICLES OF MATEER CLLED PROTONS,

NEUTRONS, AND ELECTRONS. PROTONS AND NEUTONS ARE FOUND IN THE CENTER

OF AN ATOM, WHICH IS CALLED THE NUELEUS, AND ARE LOCKED TIGHTLY 

TOGETHER BY POWERFUL FORCES. ELECTRONS SPIN UP, DOWN, AND AROUND 

OUTSIDE THE NUCLEUS WITHIN AREAS CALLED ELECTRON SHELLS.

MAKING MOLECULES 

ATOMS CAN JOIN TOGETHER -OR BOND - TO MAKE MOLECULES. 

A MOLECULES CAN BE MADE OF THE SAME ATOMS OR DIFFERENT

ONES. GASES SUCH AS HYDOGEN HAVE SIMPLE MOECULES 

MADE UP JUST TWO ATOMS, WHILE PLASTICS CAN BE MADE FROM ENDLESSLY

REPEATING MOLECULES MADE UP OF THOUSANDS OF ATOMS JOINED 

TOGETHER IN VERY LONG LINES.

HOW ATOMS BOND 

ATOMS BIND TOGETHER TO MAK MOLECULES USING THEIR ELECTRONS, WHICH THEYGIVE, TAKE, OR SHARE WITH EACH OTHER. THREE MAIN TYPES OF BOND HOLD ATOMS TOGETHER.

QUARKS AND STRINGS 

IF THE NUCLEUS OF AN ATOM IS BUILT FROM PROTONS AND NEUTRONS, WHAT ARE

THESE THINGS MADE OF? IT SEEMS THAT EACH CONSISTS OF THREE EVEN 

SMALLER PARTICLES CALLED QUARKS. SOME SCIENSISTS BELIVE THAT 

EVERYTHING IS REALLY MADE FROM VIBRATIONS OF MATTER OR ENERGY 

CALLED STRINGS. BUT SO FAR, NO ONE KNOWS WHAT, IF ANYTHING, STRINGS ARE 

MADE OF.

THE LARGE HADRON COLLIDER 

THIS GIGANTIC MACHINE RUNS FOR 27 KM (17MILES) IN ACIRCULAR TUNNEL 

BURIED 100 M  (330FT) UNDERGROUND. IT WHIZZES TWO BEAMS OF ATOMIC 

PARTICLES AROUND THE TUNNEL, IN OPPOSITE DIRECTION, AT UP TO 99.9999999

PER CENT THE SPEED OF LIGHT, AND THEN DIVERTS THEM SO THAT THEY SMASH

TOGETHER. THESE BLISTRING PARTICLES COLLISIONS ARE STUDIED USING FOUR 

DETECTORS SPACED AROUND THE LOOP CALLED ALICE, ATLAS, CMS AND LHC-B.