Science exam grade 9

As you go across a period what happens to reactivity

reactivity decreases because there are more [protons which means that there is a bigger attraction.

as you go across a period what happens to the elements

The size of the atom decreases because their are more protons.

For metals when you go down a group what happens

the size of the atom increases because their are more shells

is a compound a pure substance

Yes a compound is a pure substance

the attraction between a ion and a compound forms what

anions

What are covalent bonds?

a chemical bond that involves the sharing of electron pairs between atoms

What are ionic compounds

formed from metals and non metals

What are Isotopes.

Isotopes are atoms of the same element that have a different mass because electrons have no mass it has a different number of neutrons. Like a fat twin.

What are molecular compounds

compounds formed from two or more nonmetals

What are molecules?

atoms bonded together by covalent bonding.

What are the 7 diatomic elements?

H.O.F.Br.I.N.C.l

what do cations bond to

anions

what do molecular compounds form

compounds without metals

what does neutral mean

have an equal number of protons and protons.

What happens to the reactivity as you go down a group

the reactivity increases because the atom is bigger which means that there is less attraction between protons and valence electrons

what is a compound.

2 or more elements chemically combined

What is an alloy

a MIXTURE of 2 metals

what is an anion

A negatively charged ion

What is an cation?

A positively charged ion (metal)

What is an Ion

A charged atom

What is an Ionic compound

a metal and non metal this also completes both valence shells by giving not sharing

What is an molecular compound

2 non metals completes valence shell by sharing

What is the octete rule?

when a element fills there outer shell

When you have covalent bonds what order do you do it in.

the element that needs the most amount of electrons in the middle and add the ones that need the least at the end.

where are anions on the periodic table

right side

where are cations on the periodic table

left side

why are the diatomic elements special?

they can not be alone

why is an alloy good

takes the best qualities of both metals and combines them into one.

4 ways nitrogen is fixed

Lightning (turns 5% into nitrates), Nitrifying bacteria, Soil bacteria and Man-made

how are nutrients recycled

air, land,water, and living organisms

how do humans get their carbon and in what form

in the form of glucose and we get it by eating other organisms.

how is carbon found in the atmosphere

co2

How is CO2 put back into the atmosphere?

respiration, burning of fossil fuels, volcanoes, anything burning, weathering

what do decomposers do in the carbon cycle

return the co2 back into the atmosphere.

what do humans need carbon for

cell growth, cell repair, energy

what do producers turn co2 into

glucose

What does de-nitrifying bacteria do?

it unfixes bacteria and returns it to the atmposphere.

What is nitrogen used for

Cellular reproduction, DNA, and Proteins

what is the word equation for cellular respiration

glucose + oxygen --\> carbon dioxide + water + energy

What is the word equation for photosynthesis?

Carbon dioxide + water + Energy--\> glucose + oxygen

why do nutrients have to be recycled

because if they did not there would be none left

Substances with electrons that move easily are called

Conductors

Substances with electrons that can not move easily are called

insulators

Objects with = number of protons and electrons have a…

neutral charge

Objects that gain electrons get

\- charge

Objects that lose electrons have a

\+ charge

What is Friction

rubbing 2 insulators together

What Happens to the electrons during friction

transfering of electrons between two neutral objects

What happens when a neutral object is touched with a charged object.

When a charged object touches a neutral object electrons move from the object with more electrons (from more to less). Objects end up having the same charges 

how can an electroscope can be used to detect charge.  

electroscope detects charges by contact or induction, leaves will spread or go closer together.

Define electrical discharge

When electrons move to or from a statically charged object all at once this is called electrical discharge

Describe the process of grounding and state its importance

Connecting an object to the ground. We do this to keep things neutral. It always involves conductors

Define current electricity

When electrons are made to flow through conductors (wires) in a controlled manner this is called current electricity.

Identify the positive and negative terminals of a battery

Identify the positive and negative terminals of a battery

What is the symbol for resistance

Ω

What can affect resistance

Diameter, Length, Temperature, Material

What is a series circuit

has only 1 way for the electrons to flow

Parallel circuit

more than 1 way for electrons to flow.

Which picture is seires

Which Picture is Paralel

Nitrogen Cycle

Carbon Cycle

Food Web

\+, - charged balloon with wall

Negative rod and electroscope

group 1 metals are called

alkali metals

group 2 metals are called

alkaline earth metals

group 3 metals are called

hallogens

group 4 metals are called

noble gasses