chemistry gg Flashcards
what is chemis🌳
chemistry is the science concerned with matter, that deals with: properties of matter, changes in matter
what do chemists do
chemists, as well as observing properties and changes, also develop models to explain their observations.
-they use their knowledge to control changes and to produce new kinds of matter that have practical uses.
understanding matter: cultural views
every culture has unique ways of understanding the world
- first nations and métis people use the medicine wheel to help them understand
- the madicine wheel is organized into a pattern of 4: directions, seasons, colours, etc.
- many ancient cultures also had ways of explaining matter: greek philosophers believer that matter was made up of four elements: earth, air, fire, water
scientific understanding
a scientific model about the structure of matter did not take shape until the early 1800s
-it was determined that the smallest bit of matter was an atom
forms of matter
matter is defined as anything that has mass and takes up space
- mass is a measure of the amount of substance in an object (kg + g)
- volume is a measure of how much space and object occupies ( L, mL or cm3 )
- scientists believe that matter exists in 4 states:
solids: hold their shape
liquids: take the shape of their container
gases: can fill a container of any size
plasma: similar to gases, but very rare
classifying matter
all matter us made up of different kinds of particles
- these particles give all types of matter unique characteristics, or properties
- a property is characteristics that describes a substance
- we use properties to help classify matter
pure substances
a pure substance is made up of inky one kind of particle. it has unique properties, such as, colour, hardness, boiling point.
- elements are pure substances that cannot be broken down, gold + uranium
- compounds are pure substances made from combining two or more elements, water and carbon)
mixtures
mixtures are combinations of pure substances
-there are three types of mixtures:
•mechanical mixtures: the different substances that make up the mixture are visible. heterogeneous
•suspensions: the particles of one substance are held within the other to create a cloudy mixture. these particles can be separated using a filter so it’s called heterogeneous
•solutions: looks like one substance. homogeneous
physical properties of water
- all life on earth depends on water
- among all first nations and métis people water is sacred and treated with great respect
- about 70% of our bodies are made of water
- some plants are 95% water
- one property of water is that it sticks to itself. this property is called cohesion
- water also sticks to other substances, called adhesion
physical properties
- a physical property is a characteristic of a substance that can be observed or measured without changing it examples: colour and lustre melting point and boiling point density solubility ductility crystal shape conductivity hardness texture malleability
chemical properties
a chemical property is a characteristic of a substance that describes how it reacts when it changes into a new substance or substances
- a chemical change always results in the formation of a new substance or substances with different properties
- a chemical reaction is a process in which a chemical change occurs
examples of chemical properties
absorbing heat during a reaction combustible forms gas when heated reacts with acid reacts with water emits heat during reaction emits light during reaction forms a precipitate (solid) in a solution
patterns among the elements
by the 1700s chemists has gathered a lot of information about elements, however they still had many questions:
why some elements gases and others are metals? how many elements are there? what relationships can be found between elements?
-as time went on scientists were able to fill in the gaps left in dmitris table, proving his predictions.
-later the periodic table was rearranged by henry moseley. it is now arranged according to atomic number
Dmitri Mendeleev
in 1867, Russian chemist, Dmitri Mendelev, proposed organizing information about the elements into a table.
- he gathered all of the information he could about the the known elements and wrote it down on cards. One element per card
- he gathered information such as: colour, density, melting pliant and reactivity
- he then sorted the cards into rows and columns based on similarities in the elements properties
- mendeleevs pattens were so accurate that he was able to leave gaps where he believed undiscovered elements would fit
modern periodic table
th periodic of elements is a chart that places all of the elements in rows and columns
- the elements are organized according to their atomic number
- the rows are called periods and the columns are called groups or families
- the elements found in each group or family share some common characteristics
- the periodic table is divided in metals and non metals
protons
carry a positive charge
have a mass of one atomic mass unit (amu)
are located in the centre of an atom, called the nucleus
are equal to the atomic number
are heavy but very small
neutrons
carry a neutral charge
have a mass of one atomic mass unit (amu)
are located in the nucleus of the atom
are equal to the atomic mass minus atomic number
electrons
carry a negativ charge
have a mass of 0.0005 a.m.u.
are located outside the atom in the orbital
are equal to the number of protons in the atom
are very light and also very small
nucleus
center of an atom
the protons and neutrons are found here
orbital
the area how to side of the atom The electrons are found here also called rings and shells The first will hold two electrons The second will hold eight electrons The third will hold eight electrons
valance electrons
electrons on the outermost orbital.
these are the electrons that bond with other atoms to make larger molecules
lustre
metals: shiny
non metals: dull
malleability
metals: malleable
non metals: brittle
conductivity
metals: conductors
non metals: mostly insulators
reactivity with acid
metals: mostly yes
non metals: no
state at room temperature
metals: mostly solids
non metals: solids, liquids, gases
alloy
mixture of two or more metals
penny thing
homogeneous mixture
chemical change
physical change
change that occurs without altering the substances involved
element behaviours
all elements have definite electron arrangement. this changes when the chemical undergoes a chemical reaction
-elements tend to lose or gain revetments so that they end up with the same number valence electrons as the noble gases. they want to be like noble gases with full valence electrons on their electron shell
turning into noble gases
noble gases have a very stable structure
-for example: beryllium has two valence electrons. it will lose two electrons to have a full outer shell. the other option is for it to gain 6 electrons instead of losing two to fill the 2nd electron shell.
getting a full shell causes
an atom becomes charted when electrons are added or removed.
ions
if electrons leave or are added to an atom, tha atom becomes an ion
- if the charge on the element is positive the ion is called cation
- if the charge on the element is negative it is called an anion
- if there is no charge on the element is simply called an atom - equal number of electrons and protons
