Chemistry

What is an atom?

The smallest building unit of any matter

what are the 2 things an atom is made up of?

A nucleus and Shells/orbitals/energy levels

what are the types of subatomic particles found in an atom?

protons, electron and neutrons

where are electrons found?

in the shells/orbitals/energy levels orbiting the nucleus

what kind of subatomic particles are found in the nucleus?

protons and neurons

what is the term given for protons and neutrons together?

nucleons

what are the charges of the three subatomic particles?

protons are positive, neutrons have zero charnge/nil/neutral/no charge, and electrons have negative charges

why is an atom neutral in charge?

due to the number of positive protons in an atom are equal to the number of negative electrons in the same artom.

what are the masses of the subatomic particles?

protons: 1
neutrons: 1
electrons: 1/1840

what is the unit for measuring the mass of an atom?

a.m.u : atomic mass unit

why is the mass of the atom is concentrated inside the nucleus?

due to the mass of electrons being too small, so their mass is negligible/ignored/can be neglected

what is meant by the term atomic/proton number (small number)?

the number of positive protons inside the nucleus of an atom

what is mean by the term mass/nucleon number (big number)?

the total number of positive protons and neutrons inside the nucleus

what is meant by the term “isotopes”?

different atoms of the same element that have the same number of protons (atomic number) and different number of neutrons (mass number)

what are the two types of isotopes?

radioactive isotopes and non-radioactive isotopes

explain what radioactive isotopes are.

isotopes that emit radiation (heat energy) due to them not having a stable nucleus

explain what non-radioactive isotopes are.

isotopes that do not emit radiation (heat energy) due to them having a stable nucleus

why do isotopes share same chemical properties?

due to them having same number of electrons in their outer most shell

how to find the period of an element through electric configuration?

throught counting number of shells

how to find group of an element through electrical configuration?

throught counting the number of electrons in outer most shell

How are element arranged in the periodic table?

according to their increasing proton number

what is the name given for group 1 elements?

alkali metals

what is the name given for group 2 elements?

alkali earth metals

what is the name given for group 7 elements?

Halogens

what is the name given for group 8 elements?

Noble gases

what is the zig zag line?

a barrier that differentiates between metals and non metals

how does the non-metallic character get affected when moving to the right and to the left?

to the right: increases
to the left: decreases

how does the metallic character get affected when moving to the right and to the left?

to the right: decreases
to the left: increases

what are the physical properties of transition metals?

1- high strength (hard-tough-strong)
2-high density
3-high melting point
4-some metals show magnetism

what are the chemical properties of transition metals?

1-form coloured compounds
2-acts as catalys
3-have more than one oxidation state/ variable oxidation numbersvariable

what does it mean when an atom is saturated/stable?

has outer most shell full of electrons (noble gases)

how does an atom reach stability?

by losing, gaining or sharing electrons

what is the difference between an atom and an ion and why?

an atom has no/zero charge due to the number of electrons and protons being equal, while an ion has a charge due to the number of electrons and protons being different.

what is an ion?

a charged particle/atom by losing or gaining electron

when does a particle become positively charged, and when does it become negatively charged?

when number of electrons is higher than protons then ion is negatively charged, when number of protons is higher than electrons that ion is positively charged

what is an ionic bond?

The electrostatic attraction force between positively charged and negatively charged ions

describe the giant ionic lattice structure.

regular arrangement of alternating oppositely charged positive and negative charged ions. each ion is surrounded by 6 of the other oppositely charged ions, by strong electrostatic attraction forces.

what are the properties of ionic compounds?

1. solid at room temperature

2. usually soluble in water but not organic solvents

3. conduct electricity only when molten or aqueous, due to the presence of mobile ions

4. have high melting and boiling points: due to ionic bonds between ions being very strong, as a result of the strong electrostatic attraction forces between the ions, so it takes a lot of heat energy for these bonds to break up the lattice

what is the metallic bonding and structure?

a lattice of regularly arranged positive ions embedded in a sea of electrons, where there are electrostatic attraction forces present.

what are the differences between an ionic lattice and a metallic lattice?

1. the ionic lattice has no electrons, and the metallic lattice has no negative ions

2. the ionic lattice is a structure of alternating oppositely charges ions, metallic lattice is a structure of layers of positive ions embedded in sea of electrons

3. in ionic lattice the ngative ion is bigger than the positive ioon, in metallic lattice the positive ion is bigger than the electrons

4. the ionic lattice is strong due to it having more bonds, while metallic lattice is weaker as layers cal slide of each other.

properites of metals:

1. malleable: can be compressed into sheets

2. ductile: can be drawn into wires

3. good conductor of heat

4. good conductor of electricity

why are metals malleable and ductile?

due to layers of positive ions can slide over each other without metallic bond breaking, as well as presence of mobile electrons

why are metalls good conductors of heat?

as electrons take in heat energy, which increases their kinetic energy and start to move faster, and quickly transfer heat through the metal

why are metals good conductors of electricity?

due to mobile electrons which can move through the lattice, carrying the charge.

what is a covalent bond?

the equal sharing of pairs of electrons needed to be stable, between two non metal atoms

what is valency?

they are the electrons lost or gained by an element to become stable

what are the valencies of the groups of the periodic table?

group:

1. +1

2. +2

3. +3

4. ±4

5. -3

6. -2

7. -1

8. 0 (already stable)

9. transition elements: have more than one valency/oxidiation state

what are macromolecules?

billions of atoms bonded together in a covalent structure

what are allotropes?

different forms of the same element

describe the structure of diamond (element).

large covalent structure made up of carbon aoms, where each carbon atom is bonded to 4 other carbon atoms by strong covalent bonds in a tetrahedral structure

what are the rpoperties of diamonds?properties

1. hard: as each carbon atom is bonded to 4 other carbon atoms by strong covalent bonds in a tetrahedral structure

2. poor conductor of electricity: as there are no delocalised/mobile electrons to flow/move as each carbonn atom is bonded to 4 other carbon atoms

3. high melting and boiling point: needs lots of energy to break bonds

what are the uses of diamonds?

1. jewelery: as its shiny

2. drilling and cutting: as its very hard, sharp and strong

describe the structure of graphite:

large covalent structure made up of carbon atoms in layers, where each layer of carbon is shaped in hexagons, each carbon atom is bonded to 3 other carbon atoms by strong covalent bonds, whereas layers of carbon slide over each other due to weak do weak attraction forced between layers

what are the properties of graphite?

1. soft: as layers of hexagons are bonded by weak intermolecular forces (vander wall) forces, so layers can slide over each other easily

2. good conductor of electricity: due to presence of mobile/delocalised electron, as each carbon atom is bonded to 3 other carbon atoms only

3. very high melting and boiling points: needs alot of energy to break bonds between carbon atoms

what are the uses of graphite?

1. as lubricant: as its soft

2. electrodes: as they are good conductors of electricity

3. pencils: slippery and slide through the paper

describe the structure of sand/silicon dioxide:

a diamond like structure, where each silicon atom is bonded to 4 oxygen atoms, while each oxygen atom is bonded to 2 silicon atoms by strong covalent bonds, in a tetrahedral arrangement

what are properties of sand/silicon dioxide?

1. hard: as each silicon atom is bonded to 4 oxygen atoms, while each oxygen atom is bonded to 2 other silicon atoms by strong covalent bonds

2. poor conductor of electricity: due to the lack of delocalised/mobile electrons as they are not able to move

3. insoluble in water and organic solvents

4. very high metling point: due to very strong covalent bonds between atoms that need very high energy to break apart

what is a molecule?

a group of atoms held together by covalent bonds

what does single/double/triple covalent mean?

single covalent: 1 pair of shared electrons

double covalent: 2 pairs of shared electrons

triple covalent: 3 pairs of shared electrons

what are the properties of covalent compounds (co2)?

1. low melting and boiling points: due to weak intermolecular forces

2. do not conduct electricity: due to lack of delocalised/no mobile electrons present

3. mainly liquids and gases, few are solids

4. soluble in organic solvents but not in water

what is an element?

a pure substance made up of one type of atom, that cannot be split into anything simpler by any physical or chemical means/

what is a compound?

2 or more elements chemically bonded together

compare between compounds and mixtures:

1. a single substance——-contains more than two substances

2. composition is always the same——composition can be varied

3. formation includes a chemical reaction——-no chemical reaction takes place when made

4. properties differ from element present in compound——-properties of substances of mixutre are still preset

5. can be only broken down by chemical reactions——-substances can be seperated by physical methods

what is a mixture?

2 or more substances mixed together.