Why isn't elasticity solely determined by the slope of the demand curve?

Elasticity is not solely determined by the slope of the demand curve because elasticity also considers the responsiveness of quantity demanded to price changes. The slope of the demand curve only shows the relationship between price and quantity demanded, but elasticity takes into account the percentage change in quantity demanded relative to the percentage change in price. This means that elasticity provides a more accurate measure of how sensitive consumers are to price changes compared to just looking at the slope of the demand curve.