Match the following. 1. a positively charged ion; an atom which has lost an electron cation 2. a negatively charged ion; an atom which has gained an electron ph 3. the compound formed by the ionic bonding of a cation and anion salt 4. a measure of the hydrogen ion concentration in a solution anion

PH is the measure of hydrogen ions

A positive ion is a cation

A negative ion is an anion

1. a positively charged ion; an atom which has lost an electron - cation  

2. a negatively charged ion; an atom which has gained an electron - anion

3. the compound formed by the ionic bonding of a cation and anion - salt  

4. a measure of the hydrogen ion concentration in a solution - pH  

Explanation:

A normal atom has no charge or neutral charge because it has equal number of protons, positive particles and electrons, negative particles. But when a neutral atom loses an electron, it becomes ion with one positive charge. Positive charged atom is called cation. Similarly, when a neutral an atom on gaining an electron, becomes an ion with one negative charge. Negative charged atom is called anion. Cation and anion combined by an ionic bond to form a salt, example sodium chloride. pH is a measure of the hydrogen ion concentration in a solution.

from almost the creation of the first true maps of the earth, people started seeing how continents would be able to fit together.   in particular, people noticed that south america fits almost exactly into africa.

you should be aware that while world maps were around early in the 1600’s and better defined by the end of the 1700’s, those maps were not ‘public’ but were treated as state secrets.   and so it was not till much later that the broader ‘science’ community had access to good quality and accurate world maps.

get the whole story here…

it is now known that most of the major continental masses can be fit together in a jigsaw process.   in fact we now know that the continents were indeed once all joined together as one land mass – the supercontinent of pangaea.

if you look at most world maps you will ponder how this is evidence, as the continents really don’t appear to ‘fit’ together very well.   what you need to understand is that the vast majority of maps are drawn using a map projection that has the north and south poles (which are points) are a line the width of the map at the top and bottom.   this means that the map distorts the true shape of the earth’s land and oceans as you love closer to the poles.     some other map projections distort less, but have the map shape looking like segments of an orange.   see here for a range of map projections.   check out the way greenland changes size in each!

what is more remarkable, is the next piece of evidence when added to the shape of continents.

location of mountains and fossils

what is remarkable, when you reassemble all the continents together, the ancient mountain ranges (many now eroded to their cores) and the location of rock types and fossils all match up.