Group 7 & Group 0 (Halogens & Noble Gases)

 Halogens are very dangerous, these are the Halogens:

Florine is a poisonous yellow gas and is very reactive.

Chlorine is less reactive than fluorine but is a poisonous green gas.

Bromine is a dark brown liquid, once again the odour and liquid are poisonous, and the vapour that it creates is heavy, so you can pour out its vapour from a glass ampule

Iodine is a dark purple solid that forms poisonous purple vapours, but it is also a commonly used antiseptic in medical applications. 

Tennessine.

Atatine.

But we will mainly talk about the elements starting from Florine to Iodine, but the elements Tennnessine and Atatine are still important to remember.

All halogens exist as pairs of atoms, referred to as diatomic molecules. This term indicates that these molecules consist of two atoms. They form these pairs by sharing electrons through covalent bonds. Additionally, halogens can bond with other non-metals, such as carbon or hydrogen, using the same covalent bonding mechanism.
Chlorine bonding with Carbon can get you Carbon Tetrachloride.

Unlike the Alkali metals, the Halogens increase their boiling and melting points the further down you go on the chart.
Along with the boiling points increasing, the reactivity decreases, making the elements less reactive.

The reason why they become less reactive is because the electrons get further from the positive nucleus.

When Halogen ionic bonds with metals and collects an electron to become a minus -1 electron, we call those Halides, so we change the 'ne' at the ends of the names of the Halogens so when Bromine bonds with a metal it becomes Bromide, Iodine becomes Iodide, Chlorine becomes Chloride, and Fluorine becomes Fluoride.

Most of the time they bond with the Alkali metals, an example is Sodium Chloride, the Sodium is an alkali metal while the Chloride is a Halogen.

Another thing that Halogens do is that they do something called 'Displacement Reactions', which means that the more reactive Halogen displace the less reactive ones.

So if we pumped some Chlorine gas into a solution of potassium bromide, so the chemical numbers would be Cl(g) + 2KBr (aq), since Chlorine is more reactive than Bromine, it will displace the Bromine causing the element to become 2kCl(aq).

Something to keep in mind is that more reactive Halogens will always displace less reactive ones.

Helium.

Neon.

Argon.

Krypton.

Xenon.

Radon.

They are named the Noble Gases, these are special because they have full outer shells, causing them to be inert and being unreactive, along with that, they are non-flammable and their boiling points increase the further you go down. 

 

Surface Area to Volume Ratio

If we take a look at smaller organisms, something to take notice of is that they can use diffusion to exchange substances with their environments.
If we look at humans, we need specialised systems for transport via the heart and blood vessels, like our intestines and lungs for breathing and expelling waste.

The single-celled organisms have to constantly be doing chemical reactions to survive, like gathering amino acids, glucose and Oxygen, and getting waste like carbon dioxide out.

Everything has a Surface area to Volume ratio, for example, a cell has a higher surface area to volume ratio than a cow, as when organisms increase in size, the surface area to volume ratio decreases.

Now calculating this kind of thing is a bit confusing for organisms, instead we will use a small 1cm by 1cm by 1cm cube.

To calculate the surface area, you must first get the length and the width of one face, and multiply them together, so 1cm*1cm is 1cm^2 or 1cm squared, then you multiply it by 6 because a cube is six-sided, to get 6cm^2.
To get the volume of the cube, you need to multiply three values, which in this case is 1cm*1cm*1cm, to get 1cm^3, or 1cm cubed.
So at the end it has a ratio of 6:1, because it is six times bigger than the volume of the cube.

Now if we take another cube and instead of it being 1cm*1cm*1cm, it is 2cm, first we take one face of the cube and multiply it by its height and width (2cm*2cm), then which gives us 2cm^2, then we multiply it by six because six-sided cube then we get 24.

Then the volume is 8, by multiplying all the values 2cm*2cm*2cm, giving us 8cm^3 or 8cm cubed, so putting it into an equation would give a ratio of 24:8, which we can simplify by dividing both equations by 8, which gives us a ratio of 3:1.

The Indus River Valley civilizations

The early civilization came from the river valleys, known as the Harappans, this civilization was in the area of modern-day Pakistan in the Indus Valley, dating as far back as 7,000 BCE.

Around 3,300 to 2,000 BCE, the early Indus Civilization appeared, and that's when the Acadians and the Sumerians began interacting, and then around the 3rd millennium was when the empire of Sargon the Great was established.

Then around the mature period, which is around 2600 BCE, is where most of the advanced structures were found, and if we go to Egypt, around 2500 BCE is roughly when the Pyramids were built.

Then around 1600 BCE is considered the late Indus Valley civilization, which is where the Babylonian empire was founded.

The Punjab region in Pakistan is where most of our archaeological dig sites are about the Indus Valley Civilization, found around Harappa, which is why it is known as the Harappan civilization too, the largest site is Mohenjo-Daro in the Sindh region.
We believe that over 40,000 people were living in that region alone, with around Harappa and Mohenjo-Daro, there are over 1000 sites scattered all around both regions.

The reason why we think that this is a civilization is because of the sheer size of it all, the standardization of measurement and weight, we have found them using a measurement of 1.6mm which is precise, we can speculate that there was some cultural interchange, sin they were using bricks that were a standard size so measurements were needed.

In Mohenjo-Daro, we found some sites that these people lived in, from citadels, to public baths, and what was impressive is that we found sewerage systems for carrying waste, along with houses with wells.
Their jewellery is intricate and complicated with shells gathered from the Arabian Peninsula, and the type of jewellery was not only found at these sites but also in Mesopotamia too, and we speculate that there were probably ships transporting cargo from Mesopotamia and the now modern-day Mohenjo-Daro region. 
Materials from what is now modern-day China and India, they also had their own writing system and they also made Symbols along with a wee known symbol of a Nazi Swastikas', before Hitler used in his campaigns it is a common symbol in Hinduism, often meaning good luck,.
But we don't really know much about them, other than the stuff we found at dig sites, and since we can't decipher their writing.

One of the strangest things about the Indus Valley Civilization is 'why did it end', they seemed to be thriving with good ties and imports from other civilizations, some ideas on why it ended were maybe they were invaded, some other theories are that it was because of climate change.

As one of the earliest civilizations on earth, with speculation that their whole population may reach 5 million, they used bricks and drainage systems for sewage, non-residential buildings, and water systems.
The civilisation started declining around 1800 BCE, and the drains and waterways started to become clogged, their writing started to fade, and the weights used in measuring were starting to fall out of use.   

Around 2600 BCE, is when the early Harrapan civilization started developing urban centres, the cities of Harappa, Ganeriwala and Mohenjo-Daro in what is now modern-day Pakistan.
And Dholaviva, Kalibangan, Rakhgarhi, Rupar and Lothal in modern-day India, in baths and the sewage systems they used, fire-baked bricks since they can hold up to moisture.

Around 23,000 people lived in Harappa, which we know was a fortified city along with the religious and government centres in what is modern-day Pakistan,
The houses were built of red sand and clay, spanning over 150 hectares, which is 370 acres.
The cities had citadels, which were at the centre of the civilization. Since the Indus River had elevated areas, the Harappans fortified them to have a large, bird's-eye view of the whole area. 

Along with the expansive sewage system they made, and the public baths, we also found they had garbage collection, and they also also had a high regard for spiritual piety and hygiene. 

With their advanced architecture, they built dockyards, warehouses, granaries for grain storage, and large walls to protect them from invasions and floods.
Strangely, unlike Ancient Egypt and Mesopotamia, they did not build large structures or monuments. 

Because the standardized bricks were all the same size, we assume that they did make a measurement system of sorts. Because the bricks were uniform, we can tell that their sphere of influence was big due to the spread of civilization.

They are the first civilization that we know of that made sewage and plumbing systems, what's interesting is these systems made during this time are more effective and advanced than some 3rd world countries.
Some homes drew water from wells, and all the houses were connected to the sewage system, even the houses on the outskirts of the city, this evidently means that they had high regard for themselves to be sanitary and clean.

The Harappans also did seal making, which was used in stamps to mark goods, carvings like water buffalos, tigers and elephants were artefacts found by archaeologists.
They also made strides in metalwork, with metals like Tin, Copper, Bronze lead, and others, they also used a semi-rare gemstone, Carnelian, which is dark orange in colour, which they used in jewellery.

The Harappans also traded maritimely with others and had a trading network spanning the Middle East to central Asia. They also may have been the first to use wheeled carts pulled by oxen, and they also did shell work with their maritime imports from what is now modern-day Oman.

The majority of their imports are from places like modern-day China for jade, and India for copper and lead, they mainly traded pottery like terracotta pots, sea shells, precious metals and coloured gemstones like lapis lazuli and turquoise, pearls and jade.

They were a part of the Chalcolithic period, also known as the Copper Age, which is around 4300 - 3200 BCE, which showed an uptake of making more pottery that was very similar to the pottery by the Harappans, Turkmenistan and northern Iran. 

Then there is the early Harappan period, which is around 3200 -2600 BCE, and there are many similarities with other civilizations in their culture, By way, they make their seals and use them to mark goods, along with mystical animals like unicorns.

We also found a seal depicting Mohinjo-Daro, a half-human, half-buffalo monster fighting a tiger. This might symbolise the fighting of Gilgamesh, a known folk hero in Mesopotamian poems, and Aruru, the Sumerian earth and fertility goddess.

When we excavated these sites in the Indus Valley, we saw the art and culture of the Indus Valley civilisation, sculptures, and figures made from bronze, terracotta, and steatite.
Along with gold jewellery and a head of what we presume to be a priest wearing a robe, we have also found another statue of what we have dubbed the dancing girl. It looks like a girl with one hand on her right hip. We have also found other terracotta sculptures, including animals like bears, cows, and monkeys. 

We also know they were very organised, due to their hierarchies, their evenly sized and spaced out bricks, their seals and weights are well balanced and were similar in weight, with everything so uniform and well balanced we know that there was a kind of central government or governing body making sure it all of them were correct and proper.

Several theories say what kind of governing body they had, some say it was a central governing state, and some say that the whole thing was similar to a state-controlled area.
Meaning that the whole thing was organised by one governing body, sign that this might be true was that there was evidence that there were settlements that were nearby raw materials and similar artefacts.

There is another theory that states that the Harappan civilization had a group of leaders each governing their respective region, instead, the theory is that there is no centralized state, other people have theorised that there was no central government and everyone was considered an equal. 

We have found some written materials that gave us great insight into the Anchent Mesopotamian and Egypt civilizations, but unfortunately, since the script is so difficult to decipher the script compared to the Egyptian script Hieroglyphs which we already figured out how to read, the Indus scripts are still a mystery to us, because we can't understand the script, other than finding artefacts, the majority of our knowledge on it is purely either guesswork or with deducting what they did via clues like the fact we know they traded with others, and were sea-faring people.

We also have not come across any elite burials, meaning no graves we have found that looked to be the tomb of a king or queen or someone with high status, maybe its because they believed in a different afterlife, or didn't believe in any at all.

But this doesn't rule out the social hierarchy, as we have found that there were differently sized houses, often meaning the bigger the house the more socially or economically the person was, along with the location of the house also symbolising the amount of wealth they had.

We also believe that the Harappans were not into much warfare as they were peaceful, at least we think so as we did find weapons at dig sites but we assume they did not involve themselves in war maybe because of their location or sheer population size.

The Indus Valley Civilization started its decline around 1800 BCE, some theories are that there was a great flood, climate change or the drying of the Sarawati river which hapened around 1900 BCE.
One other theory states that the large civilization broke  up into smaller communities  which we called them the late Harappan cultures. 

Another way they could had their decline was the moonsoons, which was maybe a detrement to their livestock and crops.

The theory that mkes the most sense is during 1800 BCE decline, the Indus Valley became cooler and dryer and a potental earthquake causing the rivers to be disrupted, and causing the Harappans to move since their form of water is non-existanent, they may have tried to go to the Ganges lake in the east, but since they had a large population and they wen't able to trade since of their lack of resourses, and slowly abandoned their civilization by 1700 BCE.

Components

Components are used in circuits for electricity to flow, and we write these components via symbols.

Firstly, we write multiple vertical lines to depict a Cell or Battery, which powers the circuit.

Wires are written as lines and normally straight, and they carry the current throughout the circuit.

A Fuse is a rectangle with a wire running through it. Its purpose is to prevent the device from being overloaded. When too much power flows through the circuit, the fuse breaks, cutting power.

For switches, it will look like two circles connected via a short line between them, when the line is connected it means the current can flow, but when the switch's line isn't it means the current can't flow.

Then a Diode is a component that only allows current to flow a certain way, a form of diode is a Light Admitting Diode or LED, which lights up when electricity flows through it.

Now, for measuring current, we have Ammeters, which are put in series or connected through the circuit, and Volumeters, which are used for measuring potential difference and are  added in parallel, usually outside the circuit.

Lastly, we have resistors, which 'resist' the current to a specified amount, certain components can only function at certain amounts of electricity, if we put too much power into a component it might fry the circuits and the components might smoke or catch on fire, for example, when you charge your phone, it has resistors in the plug to not take too much power so that the internals don't fry.
Along with normal basic resistors, there are also variable resistors that can be modified so that they resist more or less current based on the situation.

Light-dependent resistors use light as a way of varying the amount of resistance, if you put them in a bright environment will resist a lot less than in a dark one as the darker it gets the more they will resist an application many people use these LDR's is in automatic nightlights which turn on when the lights in the room are off.

Thermistors use heat to vary the resistance so the more heat the less resistant the resistor becomes, and the colder it gets the more resistant it becomes.

Charge, Current & Time

A charge is a measurement of current that flows through a window of time, such as the amount of charge that flows through a wire in a minute or hour. 

We write charge with the letter Q, and the name of this measurement for change is Coulombs, so an equation of this would be:
Q=A*T, or Q (charge), is equal to A which is amps, multiplied by T, which is time usually written in seconds unless specified. 

So in an equation, it would look something like this:

    "A kettle draws 12 amps and takes 50 seconds to boil, how much charge has passed          through the wire."

Since we have amps as the voltage and we were given an amount of time, the math is easy, first, we multiply the 12 * 50, which provides us with 600 coulombs or charge.

What about another equation:

    "A phone charger takes a total charge of 43.2Kc (43.2 kilo-coulombs) over 2 hours,             what amount of current has flowed through the wire"

First, we change the equation to match the problem, so we will use:
I=Q/T.

Now, we multiply 43.2kC by 1000. Since a kilo is 1000, we convert it to 43,000c or 43,000 coulombs.
However, since we use seconds instead of hours in our equation, we have to multiply 2 hours by 60 to get 120 minutes, then another 60 to get seconds. 
Which is around 7,200 seconds, now we just plug in the 43,000 / 7,200, which gives us around 6a or 6 amps. 

The Standard of Ur

The Standard of Ur is 4500 years old and comes from the city-state of Ur now in present-day Iraq.

Normally standards are banners and flags that were used in war, but the standard of Ur is different since it was intentionally buried and found in tombs, or Royal Tombs dubbed by Leonard Woodlly excavated in the early 20s and early 30s.

But Woolly discovered one piece, which we dubbed the Standard of Ur. It might have been used as a storage device, a musical instrument, or currency.

It is a long rectangular. On one wall, an artwork depicts peace and prosperity, farmers growing crops, and cattle being moved. The rectangle is split into three registers or horizontal segments. 

The colours on the standard of Ur are interesting because many of the materials used in the standard we brought in from neighbouring civilizations.
For example, the blue on the standard was brought in from Afghanistan, the red stone from modern-day India, and the shell came from the Gulf south of now current-day Iraq.

Once again the reason why importing materials and working with other civilizations worked is because of Agriculture, as with agriculture everyone in their group did not have to worry about gathering food and was able to obtain a surplus of food, and were able to branch out to the extent of meeting other people.

Now back to the standard, on it is the 3 horizontal segments, the bottom row is mainly working-class people, depicted transporting goods to a destination.

The middle row is people with animals, some sheep and bulls, these animals might get sacrificed in the form of an income tax or service.

Lastly is the top row, with what looks to be a king on a throne with people sitting down and watching him, with an entertainer playing an instrument, and somewhat looks to be people taking an audience with the king holding cups or chalices.

Now the backside of the standard is a totally different story, it is still three horizontal rows, but now instead the back of the standard depicts a war or things that were brought into war, such as chariots and people with spears.

The bottom row is what looks to be one chariot drawn in impact frames as starts from a walk to a gallop to a sprint, pulled by male donkeys, one man maybe an enemy or ally has clearly fallen over, with blood spilling out where a horse had possibly stepped on him.

The middle row looks to be a structured army, on one half of the drawing, showing them in a line possibly marching to war, the middle standard depicts the army defeating their enemies, while the the right side depicts captured prisoners of war or POWs.

At the top row is what looks to be a large figure possibly the king is in the centre the left side has a group of soldiers and a chariot while the right side is POWs being handed to the king, they seem to not be wearing much clothing and being very bloody when being handed over.

Active Transport

Active transport works in root hair cells in plants, for example, we can use diffusion to compare it.

When we talk about diffusion it is particles going from a region of high concentration to low concentration, this takes no energy from the cell, as it is a passive process.

Active Transport is the movement of molecules that go against to concentration gradient, and that does require energy from the cell, which is ann active process. 
It also always happens across a cell membrane, in which special proteins transfer molecules across the cell membrane.

In a plant, all the energy comes from solar respiration, which happens in the mitochondria which break down glucose to create energy for the plant, and the mitochondria store the energy in things called ATP, which are basically batteries, transporting the energy from the mitochondria and moving it around the plant.

Let's take a plant as an example of active transport, this plant needs energy to function and mineral ions to survive, which it gets from the soil, which they use roots to gather these, there are cells on the roots which are named root hair cells which help absorb all the minerals the plant needs from the surrounding soil. 

The plant needs certain minerals the plant needs mainly nitrates to produce proteins and magnesium for chlorophyll since they need to gather the minerals the plant has to absorb the minerals via active transport going against their concentration gradient, the reason why the plant can't absorb the minerals via diffusion is that there is a higher concentration of magnesium and nitrates in the root cells than the soil, so active transportation is necessary, in the root hair cells are a lot of mitochondria, which help with energy in the cell.