Chemistry First monthly test

what is an element?

Pure substances made from only one type of atom and cannot be broken down further

what is a compound

Substance made from 2 or more elements that have reacted with each other and formed chemical bonds between atoms

what is a mixutre

A mixture is a substance made up of 2 or more elements or compounds but are not chemically bonded together

What is the relative charge and mass of a proton?

+1 charge: relative mass 1

What is the relative charge of a neutron

1 charge: relative mass 1

What is the relative charge of a electron

-1 charge: relative mass 1/1840

Define proton number

number of protons in a nucleus of an atom

Define mass/nucleon number

total number of protons and neutrons in the nucleus of an atom

Describe the structure of an atom

the structure of an atom has central nucleus containing nucleus and protons, it is surrounded by electrons arranged in shells

Going across a row in the periodic table is known ass

Period

Going down a column in a periodic table is know as

Group

What r group 8 elements known as

Noble gases

What is unique about the group 8 elements

they have a full outer shell and are unreactive

What are istopes

Isotopes are atoms of the same elements that have the same number of protons and electrons but different number of neutrons

why does isotopes of the same elements have the same chemical properties

because the electron configuration stays the same

whats a covalent bond

a convalent bond is formed when a pair of electrons is shared between two atoms leading to full outershell

Why do simple molecular compounds have low mp and bp?

the intermolecular forces between them are very weak so little energy is needed

Why do simple molecular compounds have poor conductivity

because there are no ions to carry any charge

Describe the structure of an ionic compound

an ionic compound has giant lattice structure; cations and anions are arranged alternatively. It is held together by strong electrostatic forces of attraction so need more energy to overcome

When do ionic compounds have good eletrical charges?

when aqueous or molten, ions are allowed to move to carry charge

why do ionic compounds have poor eletricity when solid?

ions are in a fixe position and cannot move

Describe the giant covalent structure of Diamond

Each carbon atom is covalently bonded to 4 other, Tetrahedral 3d shape, very hard due to many strong covalent bonds, cannot conduct eletricity; no delocalised electrons

Describe the giant covalent structure of Graphite

Each carbon atom is bonded to 3 other, layers of hexagonal rings with no covalent bond between layers, Layers are connected by weak intermolecular forces; can slide over each other so it is soft. one electron from each carbon atom is delocalised so can conduct eletricity as electrions carry charge

Descrbe the uses of Diamond

Cutting tools

Describe the uses of Graphite

Lubricant, Conductor

Describe the giant covalent structure of Silicon (IV) oxide, (Silicon Dioxide)

Main component of Sand. Each silicon atom is covalently bonded to 4 oxygen atoms and each oxygen is covalently bonded to 2 silicon atom.

Describe the Similarities between silicon dioxide and Diamond

In silicon, each silicon atom is covalently bonded to 4 other oxygen atoms and in diamond, each carbon atom is covalently bonded to 4 other carbon atoms. Both have High mp and bp which are hard and need lots of energy to break, Both have their atoms bonded in tetrahedral Arrangement therefore both are hard a rigid

Describe metallic bonding

Metallic bonds are the electrostatic attraction between the positive metal ions(cations) in a giant metallic lattice and a ‘sea’ of delocalised electrions

Describe the structure of metals

Metal consists of Giant structures of atoms arranged in a regular pattern

Why can metals conduct eletricity

electrons in outershell are delocalised and are free to move through the whole structure

Describe the Properties of Metals

1. Conduct Electricity
2. Malleable and ductile
3. High mp and bp