SCIENCE CHEMISTRY (Chpt 8 - Atoms & Molecules) Flashcards
Model of Matter; Atoms & Molecules
basic building blocks of matter
elements
molecule
a group of two or more atoms (elements) chemically combined
compound
a group of two or more atoms (elements) not chemically combined
variety of elements on Earth
due to differences in their simplest units
atom
simplest unit of an element. it is an electrically neutral entity that is made up of a +ve(ly) charged nucleus (protons and neutrons) with -ve(ly) charged electrons moving around the nucleus
“atom” - derived from Greek work “atomos”, which means “cannot be cut” or “indivisible”
size of atom
cannot be seen with naked eye
instruments used to observe nanoscale objects (*nanoscale objects: tiny objects with sizes less than 0.000000001metre or one-billionth of a metre)
- atomic force microscope
- scanning tunnelling microscope
nanotechnology
field of science that involved nanoscale objects and their applications
applications: very small robots (nanorobots) –> deliver drugs into bloodstream and to repair damaged cells
structure of atom
contains three sub-atomic particles
1. proton
2. neutron
3. electron
* protons and neutrons: form the nucleus of an atom
* electrons: move around nucleus
proton
relative charge: +ve(ly) charged particle
relative mass: 1
position in an atom: within the nucleus
neutron
relative charge: 0, particle with no charge
relative mass: 1
position in an atom: within the nucleus
electron
relative charge: -ve(ly) charged particle, -1
relative mass: 1/1840
position in an atom: around the nucleus (at high speed)
nucleus of atom
made up of protons and nucleus: +ve(ly) charged
mass of atom
negligible, does not add up to mass of atom
Periodic Table of Elements
to find out the number of protons in an atom of an element
number above chemical symbol of element: aka proton number
proton number: number of protons in atom of an element
e.g. proton number of helium: 2
–> helium atom contains 2 protons
